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
Rockbursts, which mainly affect mining roadways, are dynamic disasters arising from the surrounding rock under high stress. Understanding the interaction between supports and the surrounding rock is necessary for effe...Rockbursts, which mainly affect mining roadways, are dynamic disasters arising from the surrounding rock under high stress. Understanding the interaction between supports and the surrounding rock is necessary for effective rockburst control. In this study, the squeezing behavior of the surrounding rock is analyzed in rockburst roadways, and a mechanical model of rockbursts is established considering the dynamic support stress, thus deriving formulas and providing characteristic curves for describing the interaction between the support and surrounding rock. Design principles and parameters of supports for rockburst control are proposed. The results show that only when the geostress magnitude exceeds a critical value can it drive the formation of rockburst conditions. The main factors influencing the convergence response and rockburst occurrence around roadways are geostress, rock brittleness, uniaxial compressive strength, and roadway excavation size. Roadway support devices can play a role in controlling rockburst by suppressing the squeezing evolution of the surrounding rock towards instability points of rockburst. Further, the higher the strength and the longer the impact stroke of support devices with constant resistance, the more easily multiple balance points can be formed with the surrounding rock to control rockburst occurrence. Supports with long impact stroke allow adaptation to varying geostress levels around the roadway, aiding in rockburst control. The results offer a quantitative method for designing support systems for rockburst-prone roadways. The design criterion of supports is determined by the intersection between the convergence curve of the surrounding rock and the squeezing deformation curve of the support devices.展开更多
Maintaining the integrity and longevity of structures is essential in many industries,such as aerospace,nuclear,and petroleum.To achieve the cost-effectiveness of large-scale systems in petroleum drilling,a strong emp...Maintaining the integrity and longevity of structures is essential in many industries,such as aerospace,nuclear,and petroleum.To achieve the cost-effectiveness of large-scale systems in petroleum drilling,a strong emphasis on structural durability and monitoring is required.This study focuses on the mechanical vibrations that occur in rotary drilling systems,which have a substantial impact on the structural integrity of drilling equipment.The study specifically investigates axial,torsional,and lateral vibrations,which might lead to negative consequences such as bit-bounce,chaotic whirling,and high-frequency stick-slip.These events not only hinder the efficiency of drilling but also lead to exhaustion and harm to the system’s components since they are difficult to be detected and controlled in real time.The study investigates the dynamic interactions of these vibrations,specifically in their high-frequency modes,usingfield data obtained from measurement while drilling.Thefindings have demonstrated the effect of strong coupling between the high-frequency modes of these vibrations on drilling sys-tem performance.The obtained results highlight the importance of considering the interconnected impacts of these vibrations when designing and implementing robust control systems.Therefore,integrating these compo-nents can increase the durability of drill bits and drill strings,as well as improve the ability to monitor and detect damage.Moreover,by exploiting thesefindings,the assessment of structural resilience in rotary drilling systems can be enhanced.Furthermore,the study demonstrates the capacity of structural health monitoring to improve the quality,dependability,and efficiency of rotary drilling systems in the petroleum industry.展开更多
Purpose–Adding an appropriate pre-sag to the geometry of simple catenary systems for electric railways can improve their performance in dynamic interaction with the pantographs of trains operating under them.The valu...Purpose–Adding an appropriate pre-sag to the geometry of simple catenary systems for electric railways can improve their performance in dynamic interaction with the pantographs of trains operating under them.The value of pre-sag can be obtained by empirical approximation or computationally expensive optimisation.This study aims to define a simple but accurate method to determine a suitable pre-sag without dynamic simulations and to find its limitations.Design/methodology/approach–A quasi-static method to determine the ideal value of pre-sag is described based on elasticity variations.It considers variations of the static contact force.The limits of this method are investigated by comparing it to a parametric dynamic simulation study.In the dynamic simulation,an optimal level of pre-sag is identified for each contact force level.The influence of the speed in the dynamic simulation results is expressed in two parameters:the quasi-static influence in the mean contact force and the dynamic influence in the ratio between the vehicle speed and the wave propagation speed in the contact wire.Findings–The comparison between the suggested method and the dynamic simulations shows a high consistency up to a speed limit of around 40%of the wave propagation speed.The best agreement with the dynamic results is achieved by calculating the optimal pre-sag based on the absolute elasticity variation.Practical implications–The simplified approach for determining the pre-sag is valid for low-speed applications,such as suburban railway lines.For these cases,a highly suitable geometry can be obtained with the suggested method,meaning a significantly reduced computational effort.As a case study for this work,the results are applied to a Swedish suburban rail line upgrade case.Originality/value–The static uplift force is added as a varied parameter in dynamic simulations.The shift in system behaviour from low to high dynamics is described,and how the benefits from pre-sag are visible and then disappear.The limit value of the low-dynamics regime is identified to be 40%.展开更多
The formation and evolution of basins in the China continent are closely related to the collages of many blocks and orogenic belts. Based on a large amount of the geological, geophysical, petroleum exploration data an...The formation and evolution of basins in the China continent are closely related to the collages of many blocks and orogenic belts. Based on a large amount of the geological, geophysical, petroleum exploration data and a large number of published research results, the basement constitutions and evolutions of tectonic-sedimentary of sedimentary basins, the main border fault belts and the orogenesis of their peripheries of the basins are analyzed. Especially, the main typical basins in the eight divisions in the continent of China are analyzed in detail, including the Tarim, Ordos, Sichuan, Songliao, Bohai Bay, Junggar, Qiadam and Qiangtang basins. The main five stages of superimposed evolutions processes of basins revealed, which accompanied with the tectonic processes of the Paleo-Asian Ocean, Tethyan and Western Pacific domains. They contained the formations of main Cratons （1850-800 Ma）, developments of marine basins （800-386 Ma）, developments of Marine- continental transition basins and super mantle plumes （386-252 Ma）, amalgamation of China Continent and developments of continental basins （252-205 Ma） and development of the foreland basins in the western and extensional faulted basin in the eastern of China （205~0 Ma）. Therefore, large scale marine sedimentary basins existed in the relatively stable continental blocks of the Proterozoic, developed during the Neoproterozoic to Paleozoic, with the property of the intracontinental cratons and peripheral foreland basins, the multistage superimposing and late reformations of basins. The continental basins developed on the weak or preexisting divisional basements, or the remnant and reformed marine basins in the Meso-Cenozoic, are mainly the continental margins, back-arc basins, retroarc foreland basins, intracontinental rifts and pull-apart basins. The styles and intensity deformation containing the faults, folds and the structural architecture of regional unconformities of the basins, responded to the openings, subductions, closures of oceans, the continent-continent collisions and reactivation of orogenies near the basins in different periods. The evolutions of the Tianshan-Mongol-Hinggan, Kunlun-Qilian-Qinling-Dabie-Sulu, Jiangshao-Shiwandashan, Helanshan-Longmengshan, Taihang-Wuling orogenic belts, the Tibet Plateau and the Altun and Tan- Lu Fault belts have importantly influenced on the tectonic-sedimentary developments, mineralization and hydrocarbon reservoir conditions of their adjacent basins in different times. The evolutions of basins also rely on the deep structures of lithosphere and the rheological properties of the mantle. The mosaic and mirroring geological structures of the deep lithosphere reflect the pre-existed divisions and hot mantle upwelling, constrain to the origins and transforms dynamics of the basins. The leading edges of the basin tectonic dynamics will focus on the basin and mountain coupling, reconstruction of the paleotectonic-paleogeography, establishing relationship between the structural deformations of shallow surface to the deep lithosphere or asthenosphere, as well as the restoring proto-basin and depicting residual basin of the Paleozoic basin, the effects of multiple stages of volcanism and paleo- earthquake events in China.展开更多
Adaptive locomotion in different types of surfaces is of critical importance for legged robots.The knowledge of various ground substrates,especially some geological properties,plays an essential role in ensuring the l...Adaptive locomotion in different types of surfaces is of critical importance for legged robots.The knowledge of various ground substrates,especially some geological properties,plays an essential role in ensuring the legged robots'safety.In this paper,the interaction between the robots and the environments is investigated through interaction dynamics with the closed-loop system model,the compliant contact model,and the friction model,which unveil the influence of environment's geological characteristics for legged robots'locomotion.The proposed method to classify substrates is based on the interaction dynamics and the sensory-motor coordination.The foot contact forces,joint position errors,and joint motor currents,which reflect body dynamics,are measured as the sensing variables.We train and classify the features extracted from the raw data with a multilevel weighted k-Nearest Neighbor(kNN) algorithm.According to the interaction dynamics,the strategy of adaptive walking is developed by adjusting the touchdown angles and foot trajectories while lifting up and dropping down the foot.Experiments are conducted on five different substrates with quadruped robot FROG-I.The comparison with other classification methods and adaptive walking between different substrates demonstrate the effectiveness of our approach.展开更多
Interaction between beta-lactum antibiotic drug ciprofloxacin hydrochloride(CFH)and cationic surfactant cetyltrimethylammonium bromide(CTAB)was performed conductometrically in aqueous as well as in the occurrence of d...Interaction between beta-lactum antibiotic drug ciprofloxacin hydrochloride(CFH)and cationic surfactant cetyltrimethylammonium bromide(CTAB)was performed conductometrically in aqueous as well as in the occurrence of different salts(NaCl,KCl as well as NH_4Cl)over the temperature range of 298.15–323.15 K at the regular interval of 5 K.CFH drug has been suggested for the treatment of bacterial infections such as urinary tract infections and acute sinusitis.A clear critical micelle concentration(CMC)was obtained for pure CTAB as well as(CFH+CTAB)mixed systems.The decrease in CMC values of CTAB caused by the addition of CFH reveals the existence of the interaction between the components and therefore it is the indication of micelle formation at lower concentration of CTAB and their CMC values further decrease in attendance of salts.A nonlinear behavior in the CMC versus T plot was observed in all the cases.The ΔG_m^0 values are found to be negative in present study systems demonstrated the stability of the solution.The values of ΔH_m^0 and ΔS_m^0 reveal the existence of hydrophobic and electrostatic interactions between CFH and CTAB.The thermodynamic properties of transfer for the micellization were also evaluated and discussed in detail.Molecular dynamic simulation disclosed that environment of water and salts have impact on the hydrophobic interaction between CFH and CTAB.In water and salts,CTAB adopts spherical micelle in which charged hydrophilic groups are interacted with waters whereas hydrophobic tails form the core of the micelle.This hydrophobic core region is highly conserved and protected.In addition,micelle formation is more favorable in aqueous Na Cl solution than other solutions.展开更多
In this paper, before the implementation of ecological laboratory experiments, the population interaction dynamics of an algae-fish system were studied mathematically and numerically. The purpose of this study was to ...In this paper, before the implementation of ecological laboratory experiments, the population interaction dynamics of an algae-fish system were studied mathematically and numerically. The purpose of this study was to explore how filter-feeding fish population affects the growth dynamics of the algae population. Mathematically theoretical works have been pursuing the investigation of some key conditions for stability of the equilibrium and existence of Hopf bifurcation. Numerical simulation works have been parsing the discovery of the growth dynamics of the algae population in view of population interaction dynamics, which in turn could prove the feasibility of the theoretical derivation and reveal the relationship between filter-feeding fish abundance and algal biomass in fish-drift algae communiyua. Furthermore, it was successful to show that the filter-feeding fish population may be a crucial factor in controlling the proliferation of the algae population, which could also directly grasp the evolution of community dynamics. All these results were expected to be useful in the study of community dynamics and laboratory elimination experiment of the algae population.展开更多
The calculation of settling speed of coarse particles is firstly addressed, with accelerated Stokesian dynamics without adjustable parameters, in which far field force acting on the particle instead of particle veloci...The calculation of settling speed of coarse particles is firstly addressed, with accelerated Stokesian dynamics without adjustable parameters, in which far field force acting on the particle instead of particle velocity is chosen as dependent variables to consider inter-particle hydrodynamic interactions. The sedimentation of a simple cubic array of spherical particles is simulated and compared to the results available to verify and validate the numerical code and computational scheme. The improved method keeps the same computational cost of the order O（NlogN） as usual accelerated Stokesian dynamics does. Then, more realistic random suspension sedimentation is investigated with the help of Mont Carlo method. The computational results agree well with experimental fitting. Finally, the sedimentation of finer cohesive particle, which is often observed in estuary environment, is presented as a further application in coastal engineering.展开更多
The dynamics of the three coupled dipolar Bose–Einstein condensates containing N bosons is investigated within a mean-field semiclassical picture based on the coherent-state method. Varieties of periodic solutions （...The dynamics of the three coupled dipolar Bose–Einstein condensates containing N bosons is investigated within a mean-field semiclassical picture based on the coherent-state method. Varieties of periodic solutions （configured as vortex, single depleted well, and dimerlike states） are obtained analytically when the fixed points are identified on the N=constant. The system dynamics are studied via numeric integration of trimer motion equations, thus revealing macroscopic effects of population inversion and self-trapping with different initial states. In particular, the trajectory of the oscillations of the populations in each well shows how the dynamics of the condensates are effected by the presence of dipole–dipole interaction and gauge field.展开更多
This paper analyses the modal interactions in the nonlinear, size-dependent dynamics of geometrically imperfect microplates. Based on the modified couple stress theory,the equations of motion for the in-plane and out-...This paper analyses the modal interactions in the nonlinear, size-dependent dynamics of geometrically imperfect microplates. Based on the modified couple stress theory,the equations of motion for the in-plane and out-of-plane motions are obtained employing the von Kármán plate theory as well as Kirchhoff＇s hypotheses by means of the Lagrange equations. The equations of motions are solved using the pseudo-arclength continuation technique and direct timeintegration method. The system parameters are tuned to the values associated with modal interactions, and then nonlinear resonant responses and energy transfer are analysed.Nonlinear motion characteristics are shown in the form of frequency-response and force-response curves, time histories, phase-plane portraits, and fast Fourier transforms.展开更多
Motivated by recent experimental studies on coherent dynamics transfer in three interacting atoms or electron spins [Phys. Rev. Lett 114（2015） 113002, Phys. Rev. Lett 120（2018） 243604], here we study entanglement ...Motivated by recent experimental studies on coherent dynamics transfer in three interacting atoms or electron spins [Phys. Rev. Lett 114（2015） 113002, Phys. Rev. Lett 120（2018） 243604], here we study entanglement entropy transfer in three interacting qubits. We analytically calculate time evolutions of wave function, density matrix and entanglement of the system. We find that initially entangled two qubits may alternatively transfer their entanglement entropy to other two qubit pairs. Thus dynamical evolution of three interacting qubits may produce a genuine three-partite entangled state through entanglement entropy transfers. In particular, different pairwise interactions of the three qubits endow symmetric and asymmetric evolutions of the entanglement transfer,characterized by the quantum mutual information and concurrence. Finally, we discuss an experimental proposal of three Rydberg atoms for testing the entanglement dynamics transfer of this kind.展开更多
The merging of multiple vortices is a fundamental process of the dynamics of Earth＇s atmosphere and oceans. In this study, the interaction of like-signed vortices is analytically and numerically examined in a framewo...The merging of multiple vortices is a fundamental process of the dynamics of Earth＇s atmosphere and oceans. In this study, the interaction of like-signed vortices is analytically and numerically examined in a framework of two-dimensional inviscid barotropic flows. It is shown that barotropic vortex interaction turns out to be more intricate than simple merging scenarios often assumed in previous studies. Some particular configurations exist in which the vortex merging process is never complete despite strong interaction of like-signed vortices, regardless of the strengths or distances between the vortices.While the conditions for a complete vortex merging process introduced in this study appear to be too strict for most practical applications, this study suggests that careful criteria for vortex mergers should be properly defined when simulating the interaction of vortices, because the merging may not always result in a final enhanced circulation at the end of the interaction,as usually assumed in the literature.展开更多
We study the synchronization dynamics in a system of multiple interacting populations of phase oscillators. Using the dimensionality-reduction technique of Ott and Antonsen, we explore different types of synchronizati...We study the synchronization dynamics in a system of multiple interacting populations of phase oscillators. Using the dimensionality-reduction technique of Ott and Antonsen, we explore different types of synchronization dynamics when the incoherent state becomes unstable. We find that the inter-population coupling is crucial to the synchronization. When the intra-population interaction is repulsive, the local synchronization can still be maintained through the inter-population coupling. For attractive inter-population coupling, the local order parameters in different populations are of in-phase while the local synchronization are of anti-phase for repulsive inter-population coupling.展开更多
The intimate host-anion interactions will regulate thermodynamics and kinetics in the self-assembly of cationic cages mimicking biological counterparts.Herein,we report construction and transformation of three Pd(Ⅱ)-...The intimate host-anion interactions will regulate thermodynamics and kinetics in the self-assembly of cationic cages mimicking biological counterparts.Herein,we report construction and transformation of three Pd(Ⅱ)-based metal-organic cages(MOCs)depending on different anions.Stoichiometric conversions of the lantern-shaped MOC-34 into either octahedral MOC-35 or tricapped trigonal prism MOC-36 are induced by BF_(4)^(–)or NO_(3)^(–),respectively.MOC-36 is kinetically favored and can undergo quantitative conversion to the thermodynamically preferred MOC-35 upon heating,accelerated by excess BF_(4)^(–)to motivate dissociative dynamics of Pd-vertices and lower activation barrier of cage transformation.The vip encapsulation behaviors of MOC-35 and MOC-36 have also been tested.These results manifest a significance of host-anion dynamics beyond complementary anion template,shedding light on the understanding of intricate anion recognition in nature.展开更多
Dynamic wheel-rail contact forces induced by a severe form of wheel tread damage have been measured by a wheel impact load detector during full-scale field tests at different vehicle speeds.Based on laser scanning,the...Dynamic wheel-rail contact forces induced by a severe form of wheel tread damage have been measured by a wheel impact load detector during full-scale field tests at different vehicle speeds.Based on laser scanning,the measured three-dimensional damage geometry is employed in simulations of dynamic vehicle-track interaction to calibrate and verify a simulation model.The relation between the magnitude of the impact load and various operational parameters,such as vehicle speed,lateral position of wheel-rail contact,track stiffness and position of impact within a sleeper bay,is investigated.The calibrated model is later employed in simulations featuring other forms of tread damage;their effects on impact load and subsequent fatigue impact on bearings,wheel webs and subsurface initiated rolling contact fatigue of the wheel tread are assessed.The results quantify the effects of wheel tread defects and are valuable in a shift towards condition-based maintenance of running gear,and for general assessment of the severity of different types of railway wheel tread damage.展开更多
Most explanation methods are designed in an empirical manner,so exploring whether there exists a first-principles explanation of a deep neural network(DNN)becomes the next core scientific problem in explainable artifi...Most explanation methods are designed in an empirical manner,so exploring whether there exists a first-principles explanation of a deep neural network(DNN)becomes the next core scientific problem in explainable artificial intelligence(XAI).Although it is still an open problem,in this paper,we discuss whether the interaction-based explanation can serve as the first-principles explanation of a DNN.The strong explanatory power of interaction theory comes from the following aspects:(1)it establishes a new axiomatic system to quantify the decision-making logic of a DNN into a set of symbolic interaction concepts;(2)it simultaneously explains various deep learning phenomena,such as generalization power,adversarial sensitivity,representation bottleneck,and learning dynamics;(3)it provides mathematical tools that uniformly explain the mechanisms of various empirical attribution methods and empirical adversarial-transferability-boosting methods;(4)it explains the extremely complex learning dynamics of a DNN by analyzing the two-phase dynamics of interaction complexity,which further reveals the internal mechanism of why and how the generalization power/adversarial sensitivity of a DNN changes during the learning process.展开更多
Reliable traffic flow prediction is crucial for mitigating urban congestion.This paper proposes Attentionbased spatiotemporal Interactive Dynamic Graph Convolutional Network(AIDGCN),a novel architecture integrating In...Reliable traffic flow prediction is crucial for mitigating urban congestion.This paper proposes Attentionbased spatiotemporal Interactive Dynamic Graph Convolutional Network(AIDGCN),a novel architecture integrating Interactive Dynamic Graph Convolution Network(IDGCN)with Temporal Multi-Head Trend-Aware Attention.Its core innovation lies in IDGCN,which uniquely splits sequences into symmetric intervals for interactive feature sharing via dynamic graphs,and a novel attention mechanism incorporating convolutional operations to capture essential local traffic trends—addressing a critical gap in standard attention for continuous data.For 15-and 60-min forecasting on METR-LA,AIDGCN achieves MAEs of 0.75%and 0.39%,and RMSEs of 1.32%and 0.14%,respectively.In the 60-min long-term forecasting of the PEMS-BAY dataset,the AIDGCN out-performs the MRA-BGCN method by 6.28%,4.93%,and 7.17%in terms of MAE,RMSE,and MAPE,respectively.Experimental results demonstrate the superiority of our pro-posed model over state-of-the-art methods.展开更多
The dynamic responses of the Tsing Ma suspension bridge and the running behaviors of trains on the bridge under turbulent wind actions are analyzed by a three-dimensional wind-train-bridge interaction model. This mode...The dynamic responses of the Tsing Ma suspension bridge and the running behaviors of trains on the bridge under turbulent wind actions are analyzed by a three-dimensional wind-train-bridge interaction model. This model consists of a spatial finite element bridge model, a train model composed of eight 4-axle identical coaches of 27 degrees-of-freedom, and a turbulent wind model. The fluctuating wind forces, including the buffeting forces and the self-excited forces, act on the bridge only, since the train runs inside the bridge deck. The dynamic responses of the bridge are calculated and some results are compared with data measured from Typhoon York. The runnability of the train passing through the Tsing Ma suspension bridge at different speeds is researched under turbulent winds with different wind velocities. Then, the threshold curve of wind velocity for ensuring the running safety of the train in the bridge deck is proposed, from which the allowable train speed at different wind velocities can be determined. The numerical results show that rail traffic on the Tsing Ma suspension bridge should be closed as the mean wind velocity reaches 30 m/s.展开更多
The train-bridge dynamic interaction problem began with the development of railway technology, and requires an evaluation method for bridge design in order to ensure the safety and stability of the bridge and the runn...The train-bridge dynamic interaction problem began with the development of railway technology, and requires an evaluation method for bridge design in order to ensure the safety and stability of the bridge and the running train. This problem is studied using theoretical analysis, numerical simulation, and experimental study. In the train-bridge dynamic interaction system proposed in this paper, the train vehicle model is established by the rigid-body dynamics method, the bridge model is established by the finite element method, and the wheel/rail vertical and lateral interaction are simulated by the corresponding assumption and the Kalker linear creep theory, respectively. Track irregularity, structure deformation, wind load, collision load, structural damage, foundation scouring, and earthquake action are regarded as the excitation for the system. The train-bridge dynamic interaction system is solved by inter-history iteration. A case study of the dynamic response of a CRH380BL high-speed train running through a standard-design bridge in China is discussed. The dynamic responses of the vehicle and of the bridge subsystems are obtained for speeds ranging from 200 km-b-1 to 400 km.h-1, and the vibration mechanism are analyzed.展开更多
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 National Natural Science Foundation of China (No. 52304133)the National Key R&D Program of China (No. 2022YFC3004605)the Department of Science and Technology of Liaoning Province (No. 2023-BS-083)。
文摘Rockbursts, which mainly affect mining roadways, are dynamic disasters arising from the surrounding rock under high stress. Understanding the interaction between supports and the surrounding rock is necessary for effective rockburst control. In this study, the squeezing behavior of the surrounding rock is analyzed in rockburst roadways, and a mechanical model of rockbursts is established considering the dynamic support stress, thus deriving formulas and providing characteristic curves for describing the interaction between the support and surrounding rock. Design principles and parameters of supports for rockburst control are proposed. The results show that only when the geostress magnitude exceeds a critical value can it drive the formation of rockburst conditions. The main factors influencing the convergence response and rockburst occurrence around roadways are geostress, rock brittleness, uniaxial compressive strength, and roadway excavation size. Roadway support devices can play a role in controlling rockburst by suppressing the squeezing evolution of the surrounding rock towards instability points of rockburst. Further, the higher the strength and the longer the impact stroke of support devices with constant resistance, the more easily multiple balance points can be formed with the surrounding rock to control rockburst occurrence. Supports with long impact stroke allow adaptation to varying geostress levels around the roadway, aiding in rockburst control. The results offer a quantitative method for designing support systems for rockburst-prone roadways. The design criterion of supports is determined by the intersection between the convergence curve of the surrounding rock and the squeezing deformation curve of the support devices.
文摘Maintaining the integrity and longevity of structures is essential in many industries,such as aerospace,nuclear,and petroleum.To achieve the cost-effectiveness of large-scale systems in petroleum drilling,a strong emphasis on structural durability and monitoring is required.This study focuses on the mechanical vibrations that occur in rotary drilling systems,which have a substantial impact on the structural integrity of drilling equipment.The study specifically investigates axial,torsional,and lateral vibrations,which might lead to negative consequences such as bit-bounce,chaotic whirling,and high-frequency stick-slip.These events not only hinder the efficiency of drilling but also lead to exhaustion and harm to the system’s components since they are difficult to be detected and controlled in real time.The study investigates the dynamic interactions of these vibrations,specifically in their high-frequency modes,usingfield data obtained from measurement while drilling.Thefindings have demonstrated the effect of strong coupling between the high-frequency modes of these vibrations on drilling sys-tem performance.The obtained results highlight the importance of considering the interconnected impacts of these vibrations when designing and implementing robust control systems.Therefore,integrating these compo-nents can increase the durability of drill bits and drill strings,as well as improve the ability to monitor and detect damage.Moreover,by exploiting thesefindings,the assessment of structural resilience in rotary drilling systems can be enhanced.Furthermore,the study demonstrates the capacity of structural health monitoring to improve the quality,dependability,and efficiency of rotary drilling systems in the petroleum industry.
基金Trafikföorvaltningen Region Stockholm and Trafikverket for funding and supporting this study.
文摘Purpose–Adding an appropriate pre-sag to the geometry of simple catenary systems for electric railways can improve their performance in dynamic interaction with the pantographs of trains operating under them.The value of pre-sag can be obtained by empirical approximation or computationally expensive optimisation.This study aims to define a simple but accurate method to determine a suitable pre-sag without dynamic simulations and to find its limitations.Design/methodology/approach–A quasi-static method to determine the ideal value of pre-sag is described based on elasticity variations.It considers variations of the static contact force.The limits of this method are investigated by comparing it to a parametric dynamic simulation study.In the dynamic simulation,an optimal level of pre-sag is identified for each contact force level.The influence of the speed in the dynamic simulation results is expressed in two parameters:the quasi-static influence in the mean contact force and the dynamic influence in the ratio between the vehicle speed and the wave propagation speed in the contact wire.Findings–The comparison between the suggested method and the dynamic simulations shows a high consistency up to a speed limit of around 40%of the wave propagation speed.The best agreement with the dynamic results is achieved by calculating the optimal pre-sag based on the absolute elasticity variation.Practical implications–The simplified approach for determining the pre-sag is valid for low-speed applications,such as suburban railway lines.For these cases,a highly suitable geometry can be obtained with the suggested method,meaning a significantly reduced computational effort.As a case study for this work,the results are applied to a Swedish suburban rail line upgrade case.Originality/value–The static uplift force is added as a varied parameter in dynamic simulations.The shift in system behaviour from low to high dynamics is described,and how the benefits from pre-sag are visible and then disappear.The limit value of the low-dynamics regime is identified to be 40%.
基金supported by the work project of China Geological Survey(No.12120115002001-4,12120115026901)the Science Research from the Northwest Oilfield Sub–company of SINOPEC(No:KY2013–S–024)+1 种基金a Special Research Grant from Ministry of Land and Resources of the People’s Republic of China(No.201011034)the Innovation Group of National Natural Science Foundation of China(No.40921001)
文摘The formation and evolution of basins in the China continent are closely related to the collages of many blocks and orogenic belts. Based on a large amount of the geological, geophysical, petroleum exploration data and a large number of published research results, the basement constitutions and evolutions of tectonic-sedimentary of sedimentary basins, the main border fault belts and the orogenesis of their peripheries of the basins are analyzed. Especially, the main typical basins in the eight divisions in the continent of China are analyzed in detail, including the Tarim, Ordos, Sichuan, Songliao, Bohai Bay, Junggar, Qiadam and Qiangtang basins. The main five stages of superimposed evolutions processes of basins revealed, which accompanied with the tectonic processes of the Paleo-Asian Ocean, Tethyan and Western Pacific domains. They contained the formations of main Cratons （1850-800 Ma）, developments of marine basins （800-386 Ma）, developments of Marine- continental transition basins and super mantle plumes （386-252 Ma）, amalgamation of China Continent and developments of continental basins （252-205 Ma） and development of the foreland basins in the western and extensional faulted basin in the eastern of China （205~0 Ma）. Therefore, large scale marine sedimentary basins existed in the relatively stable continental blocks of the Proterozoic, developed during the Neoproterozoic to Paleozoic, with the property of the intracontinental cratons and peripheral foreland basins, the multistage superimposing and late reformations of basins. The continental basins developed on the weak or preexisting divisional basements, or the remnant and reformed marine basins in the Meso-Cenozoic, are mainly the continental margins, back-arc basins, retroarc foreland basins, intracontinental rifts and pull-apart basins. The styles and intensity deformation containing the faults, folds and the structural architecture of regional unconformities of the basins, responded to the openings, subductions, closures of oceans, the continent-continent collisions and reactivation of orogenies near the basins in different periods. The evolutions of the Tianshan-Mongol-Hinggan, Kunlun-Qilian-Qinling-Dabie-Sulu, Jiangshao-Shiwandashan, Helanshan-Longmengshan, Taihang-Wuling orogenic belts, the Tibet Plateau and the Altun and Tan- Lu Fault belts have importantly influenced on the tectonic-sedimentary developments, mineralization and hydrocarbon reservoir conditions of their adjacent basins in different times. The evolutions of basins also rely on the deep structures of lithosphere and the rheological properties of the mantle. The mosaic and mirroring geological structures of the deep lithosphere reflect the pre-existed divisions and hot mantle upwelling, constrain to the origins and transforms dynamics of the basins. The leading edges of the basin tectonic dynamics will focus on the basin and mountain coupling, reconstruction of the paleotectonic-paleogeography, establishing relationship between the structural deformations of shallow surface to the deep lithosphere or asthenosphere, as well as the restoring proto-basin and depicting residual basin of the Paleozoic basin, the effects of multiple stages of volcanism and paleo- earthquake events in China.
文摘Adaptive locomotion in different types of surfaces is of critical importance for legged robots.The knowledge of various ground substrates,especially some geological properties,plays an essential role in ensuring the legged robots'safety.In this paper,the interaction between the robots and the environments is investigated through interaction dynamics with the closed-loop system model,the compliant contact model,and the friction model,which unveil the influence of environment's geological characteristics for legged robots'locomotion.The proposed method to classify substrates is based on the interaction dynamics and the sensory-motor coordination.The foot contact forces,joint position errors,and joint motor currents,which reflect body dynamics,are measured as the sensing variables.We train and classify the features extracted from the raw data with a multilevel weighted k-Nearest Neighbor(kNN) algorithm.According to the interaction dynamics,the strategy of adaptive walking is developed by adjusting the touchdown angles and foot trajectories while lifting up and dropping down the foot.Experiments are conducted on five different substrates with quadruped robot FROG-I.The comparison with other classification methods and adaptive walking between different substrates demonstrate the effectiveness of our approach.
文摘Interaction between beta-lactum antibiotic drug ciprofloxacin hydrochloride(CFH)and cationic surfactant cetyltrimethylammonium bromide(CTAB)was performed conductometrically in aqueous as well as in the occurrence of different salts(NaCl,KCl as well as NH_4Cl)over the temperature range of 298.15–323.15 K at the regular interval of 5 K.CFH drug has been suggested for the treatment of bacterial infections such as urinary tract infections and acute sinusitis.A clear critical micelle concentration(CMC)was obtained for pure CTAB as well as(CFH+CTAB)mixed systems.The decrease in CMC values of CTAB caused by the addition of CFH reveals the existence of the interaction between the components and therefore it is the indication of micelle formation at lower concentration of CTAB and their CMC values further decrease in attendance of salts.A nonlinear behavior in the CMC versus T plot was observed in all the cases.The ΔG_m^0 values are found to be negative in present study systems demonstrated the stability of the solution.The values of ΔH_m^0 and ΔS_m^0 reveal the existence of hydrophobic and electrostatic interactions between CFH and CTAB.The thermodynamic properties of transfer for the micellization were also evaluated and discussed in detail.Molecular dynamic simulation disclosed that environment of water and salts have impact on the hydrophobic interaction between CFH and CTAB.In water and salts,CTAB adopts spherical micelle in which charged hydrophilic groups are interacted with waters whereas hydrophobic tails form the core of the micelle.This hydrophobic core region is highly conserved and protected.In addition,micelle formation is more favorable in aqueous Na Cl solution than other solutions.
文摘In this paper, before the implementation of ecological laboratory experiments, the population interaction dynamics of an algae-fish system were studied mathematically and numerically. The purpose of this study was to explore how filter-feeding fish population affects the growth dynamics of the algae population. Mathematically theoretical works have been pursuing the investigation of some key conditions for stability of the equilibrium and existence of Hopf bifurcation. Numerical simulation works have been parsing the discovery of the growth dynamics of the algae population in view of population interaction dynamics, which in turn could prove the feasibility of the theoretical derivation and reveal the relationship between filter-feeding fish abundance and algal biomass in fish-drift algae communiyua. Furthermore, it was successful to show that the filter-feeding fish population may be a crucial factor in controlling the proliferation of the algae population, which could also directly grasp the evolution of community dynamics. All these results were expected to be useful in the study of community dynamics and laboratory elimination experiment of the algae population.
基金the National Natural Science Foundation of China (10332050 and 10572144)Knowledge Innovation Program (KJCX-SW-L08)
文摘The calculation of settling speed of coarse particles is firstly addressed, with accelerated Stokesian dynamics without adjustable parameters, in which far field force acting on the particle instead of particle velocity is chosen as dependent variables to consider inter-particle hydrodynamic interactions. The sedimentation of a simple cubic array of spherical particles is simulated and compared to the results available to verify and validate the numerical code and computational scheme. The improved method keeps the same computational cost of the order O（NlogN） as usual accelerated Stokesian dynamics does. Then, more realistic random suspension sedimentation is investigated with the help of Mont Carlo method. The computational results agree well with experimental fitting. Finally, the sedimentation of finer cohesive particle, which is often observed in estuary environment, is presented as a further application in coastal engineering.
基金Project supported by the National Key Basic Research Special Foundation of China(Grant Nos.2011CB921502,2012CB821305,2009CB930701,and 2010CB922904)the National Natural Science Foundation of China(Grant Nos.10934010,11228409,and 61227902)the National Natural Science Foundation of China–The Research Grants Council(Grant Nos.11061160490 and 1386-N-HKU748/10)
文摘The dynamics of the three coupled dipolar Bose–Einstein condensates containing N bosons is investigated within a mean-field semiclassical picture based on the coherent-state method. Varieties of periodic solutions （configured as vortex, single depleted well, and dimerlike states） are obtained analytically when the fixed points are identified on the N=constant. The system dynamics are studied via numeric integration of trimer motion equations, thus revealing macroscopic effects of population inversion and self-trapping with different initial states. In particular, the trajectory of the oscillations of the populations in each well shows how the dynamics of the condensates are effected by the presence of dipole–dipole interaction and gauge field.
文摘This paper analyses the modal interactions in the nonlinear, size-dependent dynamics of geometrically imperfect microplates. Based on the modified couple stress theory,the equations of motion for the in-plane and out-of-plane motions are obtained employing the von Kármán plate theory as well as Kirchhoff＇s hypotheses by means of the Lagrange equations. The equations of motions are solved using the pseudo-arclength continuation technique and direct timeintegration method. The system parameters are tuned to the values associated with modal interactions, and then nonlinear resonant responses and energy transfer are analysed.Nonlinear motion characteristics are shown in the form of frequency-response and force-response curves, time histories, phase-plane portraits, and fast Fourier transforms.
基金Supported by the National Natural Science Foundation of China under Grant No 11534014the National Key R&D Program of China under Grant No 2017YFA0304500
文摘Motivated by recent experimental studies on coherent dynamics transfer in three interacting atoms or electron spins [Phys. Rev. Lett 114（2015） 113002, Phys. Rev. Lett 120（2018） 243604], here we study entanglement entropy transfer in three interacting qubits. We analytically calculate time evolutions of wave function, density matrix and entanglement of the system. We find that initially entangled two qubits may alternatively transfer their entanglement entropy to other two qubit pairs. Thus dynamical evolution of three interacting qubits may produce a genuine three-partite entangled state through entanglement entropy transfers. In particular, different pairwise interactions of the three qubits endow symmetric and asymmetric evolutions of the entanglement transfer,characterized by the quantum mutual information and concurrence. Finally, we discuss an experimental proposal of three Rydberg atoms for testing the entanglement dynamics transfer of this kind.
基金supported by Indiana University start-up funding
文摘The merging of multiple vortices is a fundamental process of the dynamics of Earth＇s atmosphere and oceans. In this study, the interaction of like-signed vortices is analytically and numerically examined in a framework of two-dimensional inviscid barotropic flows. It is shown that barotropic vortex interaction turns out to be more intricate than simple merging scenarios often assumed in previous studies. Some particular configurations exist in which the vortex merging process is never complete despite strong interaction of like-signed vortices, regardless of the strengths or distances between the vortices.While the conditions for a complete vortex merging process introduced in this study appear to be too strict for most practical applications, this study suggests that careful criteria for vortex mergers should be properly defined when simulating the interaction of vortices, because the merging may not always result in a final enhanced circulation at the end of the interaction,as usually assumed in the literature.
文摘We study the synchronization dynamics in a system of multiple interacting populations of phase oscillators. Using the dimensionality-reduction technique of Ott and Antonsen, we explore different types of synchronization dynamics when the incoherent state becomes unstable. We find that the inter-population coupling is crucial to the synchronization. When the intra-population interaction is repulsive, the local synchronization can still be maintained through the inter-population coupling. For attractive inter-population coupling, the local order parameters in different populations are of in-phase while the local synchronization are of anti-phase for repulsive inter-population coupling.
基金supported by the NKRD Program of China(No.2021YFA1500401)the National Natural Science Foundation of China(Nos.21821003,21890380)the LIRTP of Guangdong Pearl River Talents Program(No.2017BT01C161)。
文摘The intimate host-anion interactions will regulate thermodynamics and kinetics in the self-assembly of cationic cages mimicking biological counterparts.Herein,we report construction and transformation of three Pd(Ⅱ)-based metal-organic cages(MOCs)depending on different anions.Stoichiometric conversions of the lantern-shaped MOC-34 into either octahedral MOC-35 or tricapped trigonal prism MOC-36 are induced by BF_(4)^(–)or NO_(3)^(–),respectively.MOC-36 is kinetically favored and can undergo quantitative conversion to the thermodynamically preferred MOC-35 upon heating,accelerated by excess BF_(4)^(–)to motivate dissociative dynamics of Pd-vertices and lower activation barrier of cage transformation.The vip encapsulation behaviors of MOC-35 and MOC-36 have also been tested.These results manifest a significance of host-anion dynamics beyond complementary anion template,shedding light on the understanding of intricate anion recognition in nature.
基金funded from the European Union's Horizon 2020 research and innovation programme in the project In2Track3 under grant agreement No.101012456.
文摘Dynamic wheel-rail contact forces induced by a severe form of wheel tread damage have been measured by a wheel impact load detector during full-scale field tests at different vehicle speeds.Based on laser scanning,the measured three-dimensional damage geometry is employed in simulations of dynamic vehicle-track interaction to calibrate and verify a simulation model.The relation between the magnitude of the impact load and various operational parameters,such as vehicle speed,lateral position of wheel-rail contact,track stiffness and position of impact within a sleeper bay,is investigated.The calibrated model is later employed in simulations featuring other forms of tread damage;their effects on impact load and subsequent fatigue impact on bearings,wheel webs and subsurface initiated rolling contact fatigue of the wheel tread are assessed.The results quantify the effects of wheel tread defects and are valuable in a shift towards condition-based maintenance of running gear,and for general assessment of the severity of different types of railway wheel tread damage.
基金supported by the National Science and Technology Major Project(No.2021ZD0111602)the National Natural Science Foundation of China(Nos.62276165 and 92370115)the Shanghai Natural Science Foundation(No.24ZR1491700)。
文摘Most explanation methods are designed in an empirical manner,so exploring whether there exists a first-principles explanation of a deep neural network(DNN)becomes the next core scientific problem in explainable artificial intelligence(XAI).Although it is still an open problem,in this paper,we discuss whether the interaction-based explanation can serve as the first-principles explanation of a DNN.The strong explanatory power of interaction theory comes from the following aspects:(1)it establishes a new axiomatic system to quantify the decision-making logic of a DNN into a set of symbolic interaction concepts;(2)it simultaneously explains various deep learning phenomena,such as generalization power,adversarial sensitivity,representation bottleneck,and learning dynamics;(3)it provides mathematical tools that uniformly explain the mechanisms of various empirical attribution methods and empirical adversarial-transferability-boosting methods;(4)it explains the extremely complex learning dynamics of a DNN by analyzing the two-phase dynamics of interaction complexity,which further reveals the internal mechanism of why and how the generalization power/adversarial sensitivity of a DNN changes during the learning process.
文摘Reliable traffic flow prediction is crucial for mitigating urban congestion.This paper proposes Attentionbased spatiotemporal Interactive Dynamic Graph Convolutional Network(AIDGCN),a novel architecture integrating Interactive Dynamic Graph Convolution Network(IDGCN)with Temporal Multi-Head Trend-Aware Attention.Its core innovation lies in IDGCN,which uniquely splits sequences into symmetric intervals for interactive feature sharing via dynamic graphs,and a novel attention mechanism incorporating convolutional operations to capture essential local traffic trends—addressing a critical gap in standard attention for continuous data.For 15-and 60-min forecasting on METR-LA,AIDGCN achieves MAEs of 0.75%and 0.39%,and RMSEs of 1.32%and 0.14%,respectively.In the 60-min long-term forecasting of the PEMS-BAY dataset,the AIDGCN out-performs the MRA-BGCN method by 6.28%,4.93%,and 7.17%in terms of MAE,RMSE,and MAPE,respectively.Experimental results demonstrate the superiority of our pro-posed model over state-of-the-art methods.
基金National Natural Science Foundation of China Under Grant No.90715008, 50838006The Fundamental Research Funds for the Central Universities Under Grant No 2009JBM078
文摘The dynamic responses of the Tsing Ma suspension bridge and the running behaviors of trains on the bridge under turbulent wind actions are analyzed by a three-dimensional wind-train-bridge interaction model. This model consists of a spatial finite element bridge model, a train model composed of eight 4-axle identical coaches of 27 degrees-of-freedom, and a turbulent wind model. The fluctuating wind forces, including the buffeting forces and the self-excited forces, act on the bridge only, since the train runs inside the bridge deck. The dynamic responses of the bridge are calculated and some results are compared with data measured from Typhoon York. The runnability of the train passing through the Tsing Ma suspension bridge at different speeds is researched under turbulent winds with different wind velocities. Then, the threshold curve of wind velocity for ensuring the running safety of the train in the bridge deck is proposed, from which the allowable train speed at different wind velocities can be determined. The numerical results show that rail traffic on the Tsing Ma suspension bridge should be closed as the mean wind velocity reaches 30 m/s.
基金Acknowledgements This research is sponsored by the Major State Basic Research Development Program of China （＂973＂ Program） （2013CB036203）, the 111 Project （B13002）, and the National Natural Science Foundation of China （U1434205, U1434210, 51338001 ）.
文摘The train-bridge dynamic interaction problem began with the development of railway technology, and requires an evaluation method for bridge design in order to ensure the safety and stability of the bridge and the running train. This problem is studied using theoretical analysis, numerical simulation, and experimental study. In the train-bridge dynamic interaction system proposed in this paper, the train vehicle model is established by the rigid-body dynamics method, the bridge model is established by the finite element method, and the wheel/rail vertical and lateral interaction are simulated by the corresponding assumption and the Kalker linear creep theory, respectively. Track irregularity, structure deformation, wind load, collision load, structural damage, foundation scouring, and earthquake action are regarded as the excitation for the system. The train-bridge dynamic interaction system is solved by inter-history iteration. A case study of the dynamic response of a CRH380BL high-speed train running through a standard-design bridge in China is discussed. The dynamic responses of the vehicle and of the bridge subsystems are obtained for speeds ranging from 200 km-b-1 to 400 km.h-1, and the vibration mechanism are analyzed.
