Based on the principle of vehicle-track coupling dynamics, SIMPACK multi-body dynamics software is used to establish a C80 wagon line-coupled multi-body dynamics model with 73 degrees of freedom. And the reasonablenes...Based on the principle of vehicle-track coupling dynamics, SIMPACK multi-body dynamics software is used to establish a C80 wagon line-coupled multi-body dynamics model with 73 degrees of freedom. And the reasonableness of the line-coupled dynamics model is verified by using the maximum residual acceleration, the nonlinear critical speed of the wagon. The experimental results show that the established vehicle line coupling dynamics model meets the requirements of vehicle line coupling dynamics modeling.展开更多
It is well known that the A-square term must be considered in both cavity and circuit quantum electrodynamics systems,because it arises in the derivation from the minimal coupling Hamiltonian at any finite coupling st...It is well known that the A-square term must be considered in both cavity and circuit quantum electrodynamics systems,because it arises in the derivation from the minimal coupling Hamiltonian at any finite coupling strength.In this paper,we study the quantum Rabi model with A-square terms using the Bogoliubov operator approach.After a unitary transformation,the A-square terms can be eliminated,resulting in a modified quantum Rabi model with renormalized parameters.A transcendental function responsible for the exact solution is then derived.The presence of the A-square terms is found to significantly alter the energy spectrum.The dynamics are also studied using the obtained exact wave function,which is sensitive to the strength of the A-square terms at strong coupling.We believe that these results could be observed in future light–matter interaction systems in the ultra-strong and deep strong coupling regimes.展开更多
The complex behaviors of expansive soils,particularly their volumetric changes driven by moisture variations,pose significant challenges in urban geotechnical engineering.Although vegetation-induced moisture changes a...The complex behaviors of expansive soils,particularly their volumetric changes driven by moisture variations,pose significant challenges in urban geotechnical engineering.Although vegetation-induced moisture changes are known to affect ground movement,quantitative characterization of tree–soil interactions remains limited due to insufficient field data and unclear relationships between tree water uptake and soil response.This study investigates the mechanical behavior of expansive clay soils influenced by two Lophostemon confertus samples during a 14-month field monitoring program in Melbourne,Australia.The research methodology integrates measurements of soil displacement,total soil suction,moisture content,and tree water consumption through instrumentation and monitoring systems.Field measurements suggest that tree roots reached the limits of their water extraction capacity when total soil suction exceeded 2880 kPa within the active root zone.The spatial extent of tree-induced soil desiccation reached 0.6–0.7 times the tree height laterally and penetrated to depths of 2.5–3.3 m vertically.The mature sample,with an 86%greater crown area and a threefold larger sapwood area,exhibited 142%higher water consumption(35 kL),demonstrating the scalability of tree–soil interaction mechanisms.A multiple linear regression model was developed to quantify the coupled relationships between soil movement and key variables,achieving a high adjusted R2 value of 0.97,which provides engineers and practitioners with a practical tool for estimating ground movement near trees.These findings offer valuable insights for infrastructure design in tree-adjacent environments and can inform computational models and design codes to enable more accurate site assessments and sustainable urban development.展开更多
Fluid-structure interaction(FSI)of gas-liquid two-phase fow in the horizontal pipe is investigated numerically in the present study.The volume of fluid model and standard k-e turbulence model are integrated to simulat...Fluid-structure interaction(FSI)of gas-liquid two-phase fow in the horizontal pipe is investigated numerically in the present study.The volume of fluid model and standard k-e turbulence model are integrated to simulate the typical gas-liquid two-phase fow patterns.First,validation of the numerical model is conducted and the typical fow patterns are consistent with the Baker chart.Then,the FSI framework is established to investigate the dynamic responses of the interaction between the horizontal pipe and gas-liquid two-phase fow.The results show that the dynamic response under stratified fow condition is relatively flat and the maximum pipe deformation and equivalent stress are 1.8 mm and 7.5 MPa respectively.Meanwhile,the dynamic responses induced by slug fow,wave fow and annular fow show obvious periodic fuctuations.Furthermore,the dynamic response characteristics under slug flow condition are maximum;the maximum pipe deformation and equivalent stress can reach 4mm and 17.5 MPa,respectively.The principal direction of total deformation is different under various flow patterns.Therefore,the periodic equivalent stress will form the cyclic impact on the pipe wall and affect the fatigue life of the horizontal pipe.The present study may serve as a reference for FSI simulation under gas-liquid two-phase transport conditions.展开更多
In order to achieve the complex dynamic analysis of the self-propelled seafloor pilot miner moving on the seafloor of extremely cohesive soft soil and further to make it possible to integrate the miner system with som...In order to achieve the complex dynamic analysis of the self-propelled seafloor pilot miner moving on the seafloor of extremely cohesive soft soil and further to make it possible to integrate the miner system with some subsystems to form the complete integrated deep ocean mining pilot system and perform dynamic analysis, a new method for the dynamic modeling and analysis of the miner is proposed and developed in this paper, resulting in a simplified 3D single-body vehicle model with three translational and three rotational degrees of freedom, while the track-terrain interaction model is built by partitioning the track-terrain interface into discrete elements with parameterized force dements built on the theory of terramechanics acting on each discrete dement. To evaluate and verify the correctness and effectiveness of this new modeling and analysis method, typical comparative studies with regard to computational efficiency and solution accuracy are carried out between the traditional modeling method of building the tracked vehicle as a multi-body model and the new modeling method. In full consideration of the particMar structure design of the pilot miner, the special characteristics of the seafioor soil and the hydrodynamic force of near-seafloor currnt, the dynamic simulation analysis of the miner is performed and discussed, which can provide useful guidance and reference for the practical miner system in design and operation. This new method can not only realize the rapid dynamic simulation analysis of the miner but also make possible the integration and rapid dynamic analysis of the complete integrated deep ocean mining pilot system in further researches.展开更多
The aim of this study is to develop coupled matrix formulations to characterize the dynamic interaction between the vehicle,track,and tunnel.The vehicle–track coupled system is established in light of vehicle–track ...The aim of this study is to develop coupled matrix formulations to characterize the dynamic interaction between the vehicle,track,and tunnel.The vehicle–track coupled system is established in light of vehicle–track coupled dynamics theory.The physical characteristics and mechanical behavior of tunnel segments and rings are modeled by the finite element method,while the soil layers of the vehicle–track–tunnel(VTT)system are modeled as an assemblage of 3-D mapping infinite elements by satisfying the boundary conditions at the infinite area.With novelty,the tunnel components,such as rings and segments,have been coupled to the vehicle–track systems using a matrix coupling method for finite elements.The responses of sub-systems included in the VTT interaction are obtained simultaneously to guarantee the solution accuracy.To relieve the computer storage and save the CPU time for the large-scale VTT dynamics system with high degrees of freedoms,a cyclic calculation method is introduced.Apart from model validations,the necessity of considering the tunnel substructures such as rings and segments is demonstrated.In addition,the maximum number of elements in the tunnel segment is confirmed by numerical simulations.展开更多
A glide-plus-climb micromechanism of dislocation evolution with the formation of subgrains is pro- posed for modelling of the creep-plasticity interaction (CPI). The long-range internal stress can be divided into the ...A glide-plus-climb micromechanism of dislocation evolution with the formation of subgrains is pro- posed for modelling of the creep-plasticity interaction (CPI). The long-range internal stress can be divided into the resistance for dislocation climb in subgrain boundaries and that for dislocation glide within grains or subgrains. Their evolution equations are then derived based on dislocation dynamics. Furthermore, a unified constitutive model for CPI is developed from Orowan's formula. Theoretical calculations on the basis of this model show a very good agreement between the model prediction and experimental results of benchmark tests for 2 1/4 Cr -1 Mo steel at 600℃.展开更多
Critical dynamics of the random Ising model with long-range interaction decaying as r-(d+σ) where d is the dimensionality) is studied by the theoretic renormalization-group approach. The system is released to an evol...Critical dynamics of the random Ising model with long-range interaction decaying as r-(d+σ) where d is the dimensionality) is studied by the theoretic renormalization-group approach. The system is released to an evolution within a model A dynamics. Asymptotic scaling laws are studied in a frame of the expansion in = 2σ - d. In dimensions d ＜ 2σ. the dynamic exponent z is calculated to the second order in at the random fixed point.展开更多
Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can b...Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can be well characterized based on various stochastic excitations.A three-dimensional refined spatial random vibration analysis model of high-speed maglev train-bridge coupled system is established in this paper,in which multi-source uncertainty excitation can be considered simultaneously,and the probability density evolution method(PDEM)is adopted to reveal the system-specific uncertainty dynamic characteristic.The motion equation of the maglev vehicle model is composed of multi-rigid bodies with a total 210-degrees of freedom for each vehicle,and a refined electromagnetic force-air gap model is used to account for the interaction and coupling effect between the moving train and track beam bridges,which are directly established by using finite element method.The model is proven to be applicable by comparing with Monte Carlo simulation.By applying the proposed stochastic framework to the high maglev line,the random dynamic responses of maglev vehicles running on the bridges are studied for running safety and stability assessment.Moreover,the effects of track irregularity wavelength range under different amplitude and running speeds on the coupled system are investigated.The results show that the augmentation of train speed will move backward the sensitive wavelength interval,and track irregularity amplitude influences the response remarkably in the sensitive interval.展开更多
Urban transportation systems are facing severe challenges due to the rapid growth of the urban population,especially in China.Suspended monorail system(SMS),as a sky rail transportation form,can effectively alleviate ...Urban transportation systems are facing severe challenges due to the rapid growth of the urban population,especially in China.Suspended monorail system(SMS),as a sky rail transportation form,can effectively alleviate urban traffic congestion due to its independent right-of-way and minimal ground footprint.However,the SMS possesses a special traveling system with unique vehicle structure and bridge configuration,which results in significant differences in both the mechanisms and dynamics problems associated with train–bridge interaction(TBI)when contrasted with those of traditional railway systems.Therefore,a thorough understanding of the SMS dynamics is essential for ensuring the operational safety of the system.This article presents a state-of-the-art review of the TBI modeling methodologies,critical dynamic features,field tests,and practice of the SMS in China.Firstly,the development history,technical features,and potential dynamics problems of the SMS are briefly described,followed by the mechanical characteristics and mechanisms of the train–bridge interactive systems.Then,the modeling methodology of the fundamental elements in the suspended monorail TBI is systematically reviewed,including the suspended train subsystem,bridge subsystem,train–bridge interaction relationships,system excitations,and solution method.Further,the typical dynamic features of the TBI under various operational scenarios are elaborated,including different train speeds,a variety of line sections,and a natural wind environment.Finally,the first new energy-based SMS test line in the world is systematically introduced,including the composition and functionality of the system,the details of the conducted field tests,and the measured results of the typical dynamic responses.At the end of the paper,both the guidance on further improvement of the SMS and future research topics are proposed.展开更多
A plasma screening model that accounts for electronic exchange-correlation effects and ionic nonideality in dense quantum plasmas is proposed.This model can be used as an input in various plasma interaction models to ...A plasma screening model that accounts for electronic exchange-correlation effects and ionic nonideality in dense quantum plasmas is proposed.This model can be used as an input in various plasma interaction models to calculate scattering cross-sections and transport properties.The applicability of the proposed plasma screening model is demonstrated using the example of the temperature relaxation rate in dense hydrogen and warm dense aluminum.Additionally,the conductivity of warm dense aluminum is computed in the regime where collisions are dominated by electron-ion scattering.The results obtained are compared with available theoretical results and simulation data.展开更多
A complete characterization of the behavior in human-robot interactions(HRI) includes both: the behavioral dynamics and the control laws that characterize how the behavior is regulated with the perception data. In thi...A complete characterization of the behavior in human-robot interactions(HRI) includes both: the behavioral dynamics and the control laws that characterize how the behavior is regulated with the perception data. In this way, this work proposes a leader-follower coordinate control based on an impedance control that allows to establish a dynamic relation between social forces and motion error. For this, a scheme is presented to identify the impedance based on fictitious social forces, which are described by distance-based potential fields.As part of the validation procedure, we present an experimental comparison to select the better of two different fictitious force structures. The criteria are determined by two qualities: least impedance errors during the validation procedure and least parameter variance during the recursive estimation procedure.Finally, with the best fictitious force and its identified impedance,an impedance control is designed for a mobile robot Pioneer 3AT,which is programmed to follow a human in a structured scenario.According to results, and under the hypothesis that moving like humans will be acceptable by humans, it is believed that the proposed control improves the social acceptance of the robot for this kind of interaction.展开更多
A numerical study of ship-to-ship interaction forces is performed using a commercial CFD code,and the results are compared with experimental data and with the results of a panel method analysis.Two ship models have be...A numerical study of ship-to-ship interaction forces is performed using a commercial CFD code,and the results are compared with experimental data and with the results of a panel method analysis.Two ship models have been used in the interaction forces analysis:a tug and a tanker,advancing parallel to each other with different lateral distances and two different values of the fluid depth.Computations are carried out with four different flow models:inviscid and viscous flow with the free surface modeled as a rigid wall and inviscid and viscous flow with the deformable free surface.A fair agreement was obtained with available experimental data and results obtained by panel method.The influence of viscosity in the computations is found to be comparatively weak,while the wavemaking effects may be important,at small magnitude of the horizontal clearance.展开更多
BACKGROUND Nursing practices based on the dynamic interaction model have been shown to be superior to generic nursing practices.However,whether this model is effective in patients recovering from intracranial aneurysm...BACKGROUND Nursing practices based on the dynamic interaction model have been shown to be superior to generic nursing practices.However,whether this model is effective in patients recovering from intracranial aneurysm surgery is not well studied.AIM To investigate the effect of nursing based on a dynamic interaction model on functional rehabilitation of patients after aneurysm surgery.METHODS A total of 86 cases in our hospital with intracranial aneurysm from April 2019 to April 2021,were selected and divided into the study group and the control group,with 43 patients in each group.The control group received routine nursing,and the research group received nursing intervention based on a dynamic interaction model.The daily living ability(activities of daily living,ADL),cognitive function(Simple Intelligent Mental State Scale,MMSE),quality of life(Generic Quality of Life Inventory-74,GQOL-74),self-care ability(Exercise of Self-Care Agency scale),incidence of complications,and nursing satisfaction were recorded before and after intervention.RESULTS Before intervention,ADL(52.09±6.44),MMSE(18.03±4.11),and GQOL-74(53.68±4.34)scores in the study group were not significantly different from those in the control group(ADL:50.97±7.32,MMSE:17.59±3.82,GQOL-74:55.06±3.98)(P>0.05).After intervention,ADL(86.12±5.07),MMSE(26.64±2.66),and GQOL-74(83.13±5.67)scores in the study group were higher than those in the control group(ADL:79.81±6.35,MMSE:24.51±3.00,and GQOL-74:77.96±6.27)(P<0.05).Before intervention,self-concept(17.46±4.44),self-care skills(25.22±4.20),self-care knowledge(22.35±4.74),and self-care responsibility(15.06±3.29)scores in the study group was similar to those in the control group(self-concept:16.89±5.53,self-care skills:24.59±4.46,self-care knowledge:21.80±3.61,and self-care responsibility:14.83±3.11)(P>0.05).After the intervention,self-concept(26.01±3.18),self-care skills(37.68±6.05),self-care knowledge(45.56±5.83),and self-care responsibility(22.01±3.77)scores in the study group were higher than those in the control group(self-concept:22.97±3.46,self-care skills:33.02±5.65,selfcare skills knowledge:36.81±5.54,and self-care responsibility:17.97±3.56 points)(P<0.05).The incidence of complications in the study group(4.65%)was lower than that in the control group(18.60%)(P<0.05).Nursing satisfaction in the study group(95.35%)was higher than that in the control group(81.40%)(P<0.05).CONCLUSION Nursing intervention based on a dynamic interaction model can improve postoperative cognitive function,daily living ability,self-care ability,quality of life,and patient satisfaction,while reducing the risk of complications.展开更多
In this paper, the studies on soil-pile interaction behaviors in saturated sands under static, dynamic and cyclic lateral loads by model testing are described. By comparing with the field test results for piles in sof...In this paper, the studies on soil-pile interaction behaviors in saturated sands under static, dynamic and cyclic lateral loads by model testing are described. By comparing with the field test results for piles in soft sandy clay, a formula of p-y curves based on constitutive relationship of soils applicable for both sandy and soft clays is proposed. Good agreements are obtained in comparison with the field test results performed by other investigators abroad. A p-y hysteresis curve formula based on the modified Masing's doubling criterion is also proposed, and the results are in satisfactory agreement with field test results.展开更多
It is urgent and important to explore the dynamic evolution in comprehensive transportation green efficiency(CTGE)in the context of green development.We constructed a social development index that reflects the social ...It is urgent and important to explore the dynamic evolution in comprehensive transportation green efficiency(CTGE)in the context of green development.We constructed a social development index that reflects the social benefits of transportation services,and incorporated it into the comprehensive transportation efficiency evaluation framework as an expected output.Based on the panel data of 30 regions in China from 2003-2018,the CTGE in China was measured using the slacks-based measure-data envelopment analysis(SBM-DEA)model.Further,the dynamic evolution trends of CTGE were determined using the spatial Markov model and exploratory spatio-temporal data analysis(ESTDA)technique from a spatio-temporal perspective.The results showed that the CTGE shows a U-shaped change trend but with an overall low level and significant regional differences.The state transition of CTGE has a strong spatial dependence,and there exists the phenomenon of“club convergence”.Neighbourhood background has a significant impact on the CTGE transition types,and the spatial spillover effect is pronounced.The CTGE has an obvious positive correlation and spatial agglomeration characteristics.The geometric characteristics of the LISA time path show that the evolution process of local spatial structure and local spatial dependence of China’s CTGE is stable,but the integration of spatial evolution is weak.The spatio-temporal transition results of LISA indicate that the CTGE has obvious transfer inertness and has certain path-dependence and spatial locking characteristics,which will become the major difficulty in improving the CTGE.展开更多
Various steady models for interaction between heart and arterial system have been given in liter- ature,In our recent study,a dynamic principle,i.e.the principle of least cardiac work is proposed,and a dy- namic model...Various steady models for interaction between heart and arterial system have been given in liter- ature,In our recent study,a dynamic principle,i.e.the principle of least cardiac work is proposed,and a dy- namic model for interaction of heart and arterial system is established.Preliminary results of our experiments show that both the principle and the model are consistent with the physiological phenomena.It reveals that the pres- ent analysis may offer a new measure for the study of dynamic process of interaction between heart and arterial system.展开更多
The state of the art of dynamic interaction studies is discussed. A practical technique, the decoupling direct method for the studies, is introduced briefly and demonstrated systematically via a series of numerical ex...The state of the art of dynamic interaction studies is discussed. A practical technique, the decoupling direct method for the studies, is introduced briefly and demonstrated systematically via a series of numerical experiments. The key point of the technique, i.e. the decoupling simulation of infinite media, is further clarified in four aspects: its original formulation, Us relation with other schemes for simulating infinite media, its spurious reflection analyses and its stable implementation. Applications of the decoupling direct method to the forward problems of dynamic interaction and a challenge to cope with the related inverse problems in the next century are briefly addressed.展开更多
This article considers the direct solution of the dynamic problem of building-foundation interaction.A mathematical model of the interaction between a build ing and a deformable foundation is presented.A numerical met...This article considers the direct solution of the dynamic problem of building-foundation interaction.A mathematical model of the interaction between a build ing and a deformable foundation is presented.A numerical method of successive approximations of velocities and accelerations,varying over time,is proposed.A numerical algorithm and a computer program have been developed,and studies of free and forced oscillations of the dynamic model of the building have been carried out.Numerical experiments were conducted,and results were obtained using a frame building as an example.The results are given for a simplified model considering linear and angular displacements of the foundation slab.展开更多
The multi-body flexible morphing airfoil can improve the aerodynamic characteristics based on different flight missions continuously.Recently researches have focused on the unsteady aerodynamic characteristics of flex...The multi-body flexible morphing airfoil can improve the aerodynamic characteristics based on different flight missions continuously.Recently researches have focused on the unsteady aerodynamic characteristics of flexible wings under passive actuation.However,the unsteady aerodynamic characteristics with the fluid-structure interaction effects in the multi-body active actuation process of morphing airfoil deserve further investigation.In this paper,a fluid-structure coupled simulation method for multi-body flexible morphing airfoil with active actuation subsystem was investigated,and the aerodynamic characteristics during deformation were compared with different skin flexibility,flow field environment,actuation mode and actuation time.The numerical results show that for the steady aerodynamic,the skin flexibility can improve the stability efficiency.In the unsteady process,the change trend of the transient lift coefficient and pitching moment are consistent with those of the active drive characteristics,while the instantaneous lift-drag ratio coefficient is greatly affected by the driving mode and can be improved by increasing the driving duration.展开更多
文摘Based on the principle of vehicle-track coupling dynamics, SIMPACK multi-body dynamics software is used to establish a C80 wagon line-coupled multi-body dynamics model with 73 degrees of freedom. And the reasonableness of the line-coupled dynamics model is verified by using the maximum residual acceleration, the nonlinear critical speed of the wagon. The experimental results show that the established vehicle line coupling dynamics model meets the requirements of vehicle line coupling dynamics modeling.
基金supported by the National Science Foundation of China under Grant Nos.12305009(XYC)and 11834005(QHC)the China Postdoctoral Science Foundation under Grant No.2022M720387(XYC).
文摘It is well known that the A-square term must be considered in both cavity and circuit quantum electrodynamics systems,because it arises in the derivation from the minimal coupling Hamiltonian at any finite coupling strength.In this paper,we study the quantum Rabi model with A-square terms using the Bogoliubov operator approach.After a unitary transformation,the A-square terms can be eliminated,resulting in a modified quantum Rabi model with renormalized parameters.A transcendental function responsible for the exact solution is then derived.The presence of the A-square terms is found to significantly alter the energy spectrum.The dynamics are also studied using the obtained exact wave function,which is sensitive to the strength of the A-square terms at strong coupling.We believe that these results could be observed in future light–matter interaction systems in the ultra-strong and deep strong coupling regimes.
基金funded by the Australian Research Council via the ARC Linkage(Grant No.LP16160100649).
文摘The complex behaviors of expansive soils,particularly their volumetric changes driven by moisture variations,pose significant challenges in urban geotechnical engineering.Although vegetation-induced moisture changes are known to affect ground movement,quantitative characterization of tree–soil interactions remains limited due to insufficient field data and unclear relationships between tree water uptake and soil response.This study investigates the mechanical behavior of expansive clay soils influenced by two Lophostemon confertus samples during a 14-month field monitoring program in Melbourne,Australia.The research methodology integrates measurements of soil displacement,total soil suction,moisture content,and tree water consumption through instrumentation and monitoring systems.Field measurements suggest that tree roots reached the limits of their water extraction capacity when total soil suction exceeded 2880 kPa within the active root zone.The spatial extent of tree-induced soil desiccation reached 0.6–0.7 times the tree height laterally and penetrated to depths of 2.5–3.3 m vertically.The mature sample,with an 86%greater crown area and a threefold larger sapwood area,exhibited 142%higher water consumption(35 kL),demonstrating the scalability of tree–soil interaction mechanisms.A multiple linear regression model was developed to quantify the coupled relationships between soil movement and key variables,achieving a high adjusted R2 value of 0.97,which provides engineers and practitioners with a practical tool for estimating ground movement near trees.These findings offer valuable insights for infrastructure design in tree-adjacent environments and can inform computational models and design codes to enable more accurate site assessments and sustainable urban development.
基金the National Natural Science Foundation of China(No.51779143)the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University(No.SL2020ZD101)the Cultivation of Scientific Research Ability of Young Talents of Shanghai Jiao Tong University(No.19X100040072)。
文摘Fluid-structure interaction(FSI)of gas-liquid two-phase fow in the horizontal pipe is investigated numerically in the present study.The volume of fluid model and standard k-e turbulence model are integrated to simulate the typical gas-liquid two-phase fow patterns.First,validation of the numerical model is conducted and the typical fow patterns are consistent with the Baker chart.Then,the FSI framework is established to investigate the dynamic responses of the interaction between the horizontal pipe and gas-liquid two-phase fow.The results show that the dynamic response under stratified fow condition is relatively flat and the maximum pipe deformation and equivalent stress are 1.8 mm and 7.5 MPa respectively.Meanwhile,the dynamic responses induced by slug fow,wave fow and annular fow show obvious periodic fuctuations.Furthermore,the dynamic response characteristics under slug flow condition are maximum;the maximum pipe deformation and equivalent stress can reach 4mm and 17.5 MPa,respectively.The principal direction of total deformation is different under various flow patterns.Therefore,the periodic equivalent stress will form the cyclic impact on the pipe wall and affect the fatigue life of the horizontal pipe.The present study may serve as a reference for FSI simulation under gas-liquid two-phase transport conditions.
基金supported by the National High Technology Research and Development Program of China(863 Program, Grant No.2006AA09Z240)the National Deep-Sea Technology Project of Development and Re-search(Grant No.DYXM-115-04-02-01)
文摘In order to achieve the complex dynamic analysis of the self-propelled seafloor pilot miner moving on the seafloor of extremely cohesive soft soil and further to make it possible to integrate the miner system with some subsystems to form the complete integrated deep ocean mining pilot system and perform dynamic analysis, a new method for the dynamic modeling and analysis of the miner is proposed and developed in this paper, resulting in a simplified 3D single-body vehicle model with three translational and three rotational degrees of freedom, while the track-terrain interaction model is built by partitioning the track-terrain interface into discrete elements with parameterized force dements built on the theory of terramechanics acting on each discrete dement. To evaluate and verify the correctness and effectiveness of this new modeling and analysis method, typical comparative studies with regard to computational efficiency and solution accuracy are carried out between the traditional modeling method of building the tracked vehicle as a multi-body model and the new modeling method. In full consideration of the particMar structure design of the pilot miner, the special characteristics of the seafioor soil and the hydrodynamic force of near-seafloor currnt, the dynamic simulation analysis of the miner is performed and discussed, which can provide useful guidance and reference for the practical miner system in design and operation. This new method can not only realize the rapid dynamic simulation analysis of the miner but also make possible the integration and rapid dynamic analysis of the complete integrated deep ocean mining pilot system in further researches.
基金supported by the National Natural Science Foundation of China(Grant Nos.52008404,11790283,and 51735012).
文摘The aim of this study is to develop coupled matrix formulations to characterize the dynamic interaction between the vehicle,track,and tunnel.The vehicle–track coupled system is established in light of vehicle–track coupled dynamics theory.The physical characteristics and mechanical behavior of tunnel segments and rings are modeled by the finite element method,while the soil layers of the vehicle–track–tunnel(VTT)system are modeled as an assemblage of 3-D mapping infinite elements by satisfying the boundary conditions at the infinite area.With novelty,the tunnel components,such as rings and segments,have been coupled to the vehicle–track systems using a matrix coupling method for finite elements.The responses of sub-systems included in the VTT interaction are obtained simultaneously to guarantee the solution accuracy.To relieve the computer storage and save the CPU time for the large-scale VTT dynamics system with high degrees of freedoms,a cyclic calculation method is introduced.Apart from model validations,the necessity of considering the tunnel substructures such as rings and segments is demonstrated.In addition,the maximum number of elements in the tunnel segment is confirmed by numerical simulations.
文摘A glide-plus-climb micromechanism of dislocation evolution with the formation of subgrains is pro- posed for modelling of the creep-plasticity interaction (CPI). The long-range internal stress can be divided into the resistance for dislocation climb in subgrain boundaries and that for dislocation glide within grains or subgrains. Their evolution equations are then derived based on dislocation dynamics. Furthermore, a unified constitutive model for CPI is developed from Orowan's formula. Theoretical calculations on the basis of this model show a very good agreement between the model prediction and experimental results of benchmark tests for 2 1/4 Cr -1 Mo steel at 600℃.
文摘Critical dynamics of the random Ising model with long-range interaction decaying as r-(d+σ) where d is the dimensionality) is studied by the theoretic renormalization-group approach. The system is released to an evolution within a model A dynamics. Asymptotic scaling laws are studied in a frame of the expansion in = 2σ - d. In dimensions d ＜ 2σ. the dynamic exponent z is calculated to the second order in at the random fixed point.
基金Project(2023YFB4302500)supported by the National Key R&D Program of ChinaProject(52078485)supported by the National Natural Science Foundation of ChinaProjects(2021-Major-16,2021-Special-08)supported by the Science and Technology Research and Development Program Project of China Railway Group Limited。
文摘Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can be well characterized based on various stochastic excitations.A three-dimensional refined spatial random vibration analysis model of high-speed maglev train-bridge coupled system is established in this paper,in which multi-source uncertainty excitation can be considered simultaneously,and the probability density evolution method(PDEM)is adopted to reveal the system-specific uncertainty dynamic characteristic.The motion equation of the maglev vehicle model is composed of multi-rigid bodies with a total 210-degrees of freedom for each vehicle,and a refined electromagnetic force-air gap model is used to account for the interaction and coupling effect between the moving train and track beam bridges,which are directly established by using finite element method.The model is proven to be applicable by comparing with Monte Carlo simulation.By applying the proposed stochastic framework to the high maglev line,the random dynamic responses of maglev vehicles running on the bridges are studied for running safety and stability assessment.Moreover,the effects of track irregularity wavelength range under different amplitude and running speeds on the coupled system are investigated.The results show that the augmentation of train speed will move backward the sensitive wavelength interval,and track irregularity amplitude influences the response remarkably in the sensitive interval.
基金supported by the National Natural Science Foundation of China(Grant Nos.52202483,52108476,and 52388102)。
文摘Urban transportation systems are facing severe challenges due to the rapid growth of the urban population,especially in China.Suspended monorail system(SMS),as a sky rail transportation form,can effectively alleviate urban traffic congestion due to its independent right-of-way and minimal ground footprint.However,the SMS possesses a special traveling system with unique vehicle structure and bridge configuration,which results in significant differences in both the mechanisms and dynamics problems associated with train–bridge interaction(TBI)when contrasted with those of traditional railway systems.Therefore,a thorough understanding of the SMS dynamics is essential for ensuring the operational safety of the system.This article presents a state-of-the-art review of the TBI modeling methodologies,critical dynamic features,field tests,and practice of the SMS in China.Firstly,the development history,technical features,and potential dynamics problems of the SMS are briefly described,followed by the mechanical characteristics and mechanisms of the train–bridge interactive systems.Then,the modeling methodology of the fundamental elements in the suspended monorail TBI is systematically reviewed,including the suspended train subsystem,bridge subsystem,train–bridge interaction relationships,system excitations,and solution method.Further,the typical dynamic features of the TBI under various operational scenarios are elaborated,including different train speeds,a variety of line sections,and a natural wind environment.Finally,the first new energy-based SMS test line in the world is systematically introduced,including the composition and functionality of the system,the details of the conducted field tests,and the measured results of the typical dynamic responses.At the end of the paper,both the guidance on further improvement of the SMS and future research topics are proposed.
基金funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan Grant No.AP19678033“The study of the transport and optical properties of hydrogen at high pressure.”。
文摘A plasma screening model that accounts for electronic exchange-correlation effects and ionic nonideality in dense quantum plasmas is proposed.This model can be used as an input in various plasma interaction models to calculate scattering cross-sections and transport properties.The applicability of the proposed plasma screening model is demonstrated using the example of the temperature relaxation rate in dense hydrogen and warm dense aluminum.Additionally,the conductivity of warm dense aluminum is computed in the regime where collisions are dominated by electron-ion scattering.The results obtained are compared with available theoretical results and simulation data.
文摘A complete characterization of the behavior in human-robot interactions(HRI) includes both: the behavioral dynamics and the control laws that characterize how the behavior is regulated with the perception data. In this way, this work proposes a leader-follower coordinate control based on an impedance control that allows to establish a dynamic relation between social forces and motion error. For this, a scheme is presented to identify the impedance based on fictitious social forces, which are described by distance-based potential fields.As part of the validation procedure, we present an experimental comparison to select the better of two different fictitious force structures. The criteria are determined by two qualities: least impedance errors during the validation procedure and least parameter variance during the recursive estimation procedure.Finally, with the best fictitious force and its identified impedance,an impedance control is designed for a mobile robot Pioneer 3AT,which is programmed to follow a human in a structured scenario.According to results, and under the hypothesis that moving like humans will be acceptable by humans, it is believed that the proposed control improves the social acceptance of the robot for this kind of interaction.
基金the project PTDC/EMSTRA/5628/2014 "Maneuvering and moored ships in ports-physical and numerical modeling,"funded by the Portuguese Foundation for Science and Technology(FCT)financed by FCT under contract number SFRH/BD/67070/2009
文摘A numerical study of ship-to-ship interaction forces is performed using a commercial CFD code,and the results are compared with experimental data and with the results of a panel method analysis.Two ship models have been used in the interaction forces analysis:a tug and a tanker,advancing parallel to each other with different lateral distances and two different values of the fluid depth.Computations are carried out with four different flow models:inviscid and viscous flow with the free surface modeled as a rigid wall and inviscid and viscous flow with the deformable free surface.A fair agreement was obtained with available experimental data and results obtained by panel method.The influence of viscosity in the computations is found to be comparatively weak,while the wavemaking effects may be important,at small magnitude of the horizontal clearance.
文摘BACKGROUND Nursing practices based on the dynamic interaction model have been shown to be superior to generic nursing practices.However,whether this model is effective in patients recovering from intracranial aneurysm surgery is not well studied.AIM To investigate the effect of nursing based on a dynamic interaction model on functional rehabilitation of patients after aneurysm surgery.METHODS A total of 86 cases in our hospital with intracranial aneurysm from April 2019 to April 2021,were selected and divided into the study group and the control group,with 43 patients in each group.The control group received routine nursing,and the research group received nursing intervention based on a dynamic interaction model.The daily living ability(activities of daily living,ADL),cognitive function(Simple Intelligent Mental State Scale,MMSE),quality of life(Generic Quality of Life Inventory-74,GQOL-74),self-care ability(Exercise of Self-Care Agency scale),incidence of complications,and nursing satisfaction were recorded before and after intervention.RESULTS Before intervention,ADL(52.09±6.44),MMSE(18.03±4.11),and GQOL-74(53.68±4.34)scores in the study group were not significantly different from those in the control group(ADL:50.97±7.32,MMSE:17.59±3.82,GQOL-74:55.06±3.98)(P>0.05).After intervention,ADL(86.12±5.07),MMSE(26.64±2.66),and GQOL-74(83.13±5.67)scores in the study group were higher than those in the control group(ADL:79.81±6.35,MMSE:24.51±3.00,and GQOL-74:77.96±6.27)(P<0.05).Before intervention,self-concept(17.46±4.44),self-care skills(25.22±4.20),self-care knowledge(22.35±4.74),and self-care responsibility(15.06±3.29)scores in the study group was similar to those in the control group(self-concept:16.89±5.53,self-care skills:24.59±4.46,self-care knowledge:21.80±3.61,and self-care responsibility:14.83±3.11)(P>0.05).After the intervention,self-concept(26.01±3.18),self-care skills(37.68±6.05),self-care knowledge(45.56±5.83),and self-care responsibility(22.01±3.77)scores in the study group were higher than those in the control group(self-concept:22.97±3.46,self-care skills:33.02±5.65,selfcare skills knowledge:36.81±5.54,and self-care responsibility:17.97±3.56 points)(P<0.05).The incidence of complications in the study group(4.65%)was lower than that in the control group(18.60%)(P<0.05).Nursing satisfaction in the study group(95.35%)was higher than that in the control group(81.40%)(P<0.05).CONCLUSION Nursing intervention based on a dynamic interaction model can improve postoperative cognitive function,daily living ability,self-care ability,quality of life,and patient satisfaction,while reducing the risk of complications.
文摘In this paper, the studies on soil-pile interaction behaviors in saturated sands under static, dynamic and cyclic lateral loads by model testing are described. By comparing with the field test results for piles in soft sandy clay, a formula of p-y curves based on constitutive relationship of soils applicable for both sandy and soft clays is proposed. Good agreements are obtained in comparison with the field test results performed by other investigators abroad. A p-y hysteresis curve formula based on the modified Masing's doubling criterion is also proposed, and the results are in satisfactory agreement with field test results.
基金National Key Research and Development Program of China(2019YFB1600400)National Natural Science Foundation of China(72174035)+2 种基金National Natural Science Foundation of China(71774018)Liaoning Revitalization Talents Program(XLYC2008030)Liaoning Provincial Natural Science Foundation Shipping Joint Foundation Program(2020-HYLH-20)。
文摘It is urgent and important to explore the dynamic evolution in comprehensive transportation green efficiency(CTGE)in the context of green development.We constructed a social development index that reflects the social benefits of transportation services,and incorporated it into the comprehensive transportation efficiency evaluation framework as an expected output.Based on the panel data of 30 regions in China from 2003-2018,the CTGE in China was measured using the slacks-based measure-data envelopment analysis(SBM-DEA)model.Further,the dynamic evolution trends of CTGE were determined using the spatial Markov model and exploratory spatio-temporal data analysis(ESTDA)technique from a spatio-temporal perspective.The results showed that the CTGE shows a U-shaped change trend but with an overall low level and significant regional differences.The state transition of CTGE has a strong spatial dependence,and there exists the phenomenon of“club convergence”.Neighbourhood background has a significant impact on the CTGE transition types,and the spatial spillover effect is pronounced.The CTGE has an obvious positive correlation and spatial agglomeration characteristics.The geometric characteristics of the LISA time path show that the evolution process of local spatial structure and local spatial dependence of China’s CTGE is stable,but the integration of spatial evolution is weak.The spatio-temporal transition results of LISA indicate that the CTGE has obvious transfer inertness and has certain path-dependence and spatial locking characteristics,which will become the major difficulty in improving the CTGE.
文摘Various steady models for interaction between heart and arterial system have been given in liter- ature,In our recent study,a dynamic principle,i.e.the principle of least cardiac work is proposed,and a dy- namic model for interaction of heart and arterial system is established.Preliminary results of our experiments show that both the principle and the model are consistent with the physiological phenomena.It reveals that the pres- ent analysis may offer a new measure for the study of dynamic process of interaction between heart and arterial system.
基金This paper is one of the lectures presented at "IUGG/CSB International Training Course on Continental Earthquakes and Seismic Hazard" held in Beijing, China on October 4 to 14, 1998.
文摘The state of the art of dynamic interaction studies is discussed. A practical technique, the decoupling direct method for the studies, is introduced briefly and demonstrated systematically via a series of numerical experiments. The key point of the technique, i.e. the decoupling simulation of infinite media, is further clarified in four aspects: its original formulation, Us relation with other schemes for simulating infinite media, its spurious reflection analyses and its stable implementation. Applications of the decoupling direct method to the forward problems of dynamic interaction and a challenge to cope with the related inverse problems in the next century are briefly addressed.
文摘This article considers the direct solution of the dynamic problem of building-foundation interaction.A mathematical model of the interaction between a build ing and a deformable foundation is presented.A numerical method of successive approximations of velocities and accelerations,varying over time,is proposed.A numerical algorithm and a computer program have been developed,and studies of free and forced oscillations of the dynamic model of the building have been carried out.Numerical experiments were conducted,and results were obtained using a frame building as an example.The results are given for a simplified model considering linear and angular displacements of the foundation slab.
基金supported by the National Natural Science Foundation of China(Nos.52192633,11872293)the Natural Science Foundation of Shaanxi Province,China(No.2022JC-03)。
文摘The multi-body flexible morphing airfoil can improve the aerodynamic characteristics based on different flight missions continuously.Recently researches have focused on the unsteady aerodynamic characteristics of flexible wings under passive actuation.However,the unsteady aerodynamic characteristics with the fluid-structure interaction effects in the multi-body active actuation process of morphing airfoil deserve further investigation.In this paper,a fluid-structure coupled simulation method for multi-body flexible morphing airfoil with active actuation subsystem was investigated,and the aerodynamic characteristics during deformation were compared with different skin flexibility,flow field environment,actuation mode and actuation time.The numerical results show that for the steady aerodynamic,the skin flexibility can improve the stability efficiency.In the unsteady process,the change trend of the transient lift coefficient and pitching moment are consistent with those of the active drive characteristics,while the instantaneous lift-drag ratio coefficient is greatly affected by the driving mode and can be improved by increasing the driving duration.
