A novel refined dynamic model of high-speed maglev train-bridge coupled system for random vibration and running safety assessment

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.

A Train-Bridge Dynamic Interaction Analysis Method and Its Experimental Validation

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.

Theory of Dynamic Interactions: Laws of Motion

The aim of this paper is to present the laws of motion that can be derived from the Theory of Dynamic Interactions, and of its multiple and significant scientific applications. Based on a new interpretation on the behaviour of rigid bodies exposed to simultaneous non-coaxial rotations, we have developed a hypothesis regarding the dynamic behaviour of these bodies. From these hypotheses and following the observation of the behaviour of free bodies in space, we have developed axioms and a mathematical-physical model. Consequently, we have deduced a movement equation, coherent with the hypotheses and the observed behaviour. This dynamic model, in the case of rigid solid bodies or systems, allows putting forward a series of laws and corollaries in relation to its dynamic performance. These laws have subsequently been confirmed by experimental tests. The whole of this research constitutes a rational and conceptual structure which we have named Theory of Dynamic Interactions (TID). This logical deductive system allows predicting the behaviour of solid bodies subject to multiple accelerations by rotation. In the conclusions, we underline that coherence has been obtained between the principles and axioms, the developed physical-mathematical model, the obtained movement equation, the deduced laws and the realised experimental tests.

Dynamical Interaction Between Information and Disease Spreading in Populations of Moving Agents

Considering dynamical disease spreading network consisting of moving individuals,a new double-layer network is constructed,one where the information dissemination process takes place and the other where the dynamics of disease spreading evolves.On the basis of Markov chains theory,a new model characterizing the coupled dynamics between information dissemination and disease spreading in populations of moving agents is established and corresponding state probability equations are formulated to describe the probability in each state of every node at each moment.Monte Carlo simulations are performed to characterize the interaction process between information and disease spreading and investigate factors that influence spreading dynamics.Simulation results show that the increasing of information transmission rate can reduce the scale of disease spreading in some degree.Shortening infection period and strengthening consciousness for self-protection by decreasing individual’s scope of activity both can effectively reduce the final refractory density for the disease but have less effect on the information dissemination.In addition,the increasing of vaccination rate or decreasing of long-range travel can also reduce the scale of disease spreading.

Dynamic Response of Fluid-Single Leg Gravity Platform-Soil Interaction System

An approximate method is presented to investigate the earthquake response of the fluid-single leg (shortened for S. L.) gravity platform-soil interaction system. By assuming a suitable form of the velocity potential of the radiation waves and by using the motion equation and the boundary conditions, the unknown coefficients can be obtained. Thereafter the function of frequency for the interaction system may also be obtained. In this paper, the difference of the system dynamic response between rigid foundation is analyzed and the influences of the various foundation geometric dimension and the various water-depth on the hydrodynamic loading and dynamic response of the system is illustrated.

The Pendulum of Dynamic Interactions

In this paper, we present evidence to show that the dynamics of rigid solid bodies is not a closed discipline, particularly in the field of rotational dynamics. From the observation of bodies with intrinsic rotation in our universe, our research group proposes new dynamic hypotheses that explain the behaviour observed when these bodies are subject to new simultaneous non-coaxial rotations. A new gyroscopic conical pendulum was designed for this purpose. Experimental tests initially conducted with this new gyroscopic conical pendulum were repeated for their recording on video, which accompanied this paper for better understanding thereof. These experimental tests positively confirm the new Theory of Dynamic Interactions, and its dynamic laws, which help us to understand the behaviour of this pendulum and, in general, that of the baryonic mass when it is subject to non-coaxial simultaneous rotations. It thus provides a better understanding of the nature and the dynamic behaviour of our universe.

Dynamic Interactions in the Atmosphere

Even today, with the great progress that has been made in the scientific, technological and computational fields, we are still stunned by the devastating effects brought about by atmospheric phenomena. This paper aims to propose new hypotheses in the field of dynamics to enhance our understanding of the behaviour of atmospheric disturbances caused by rotating winds. I believe that the criteria of classical dynamics that are applied to vortex systems in the atmosphere should be rigorously reviewed. I propose to establish new hypotheses in the field of dynamics, in order to better interpret rotation in nature. These hypotheses have been structured into a new theory that has been tested experimentally by both ourselves and third parties, with positive results. I propose to use the Theory of Dynamic Interactions (TDI) to interpret the behaviour of systems undergoing successive rotations around different axes—which we will refer to as non-coaxial rotations. I hold that this theory applies to air masses and groups of particles in suspension that are accelerated by rotations. Accordingly, it should be used to interpret the behaviour of tornadoes, cyclones and hurricanes. I believe that this proposal could enhance our understanding of these atmospheric phenomena and improve predictions about them.

Modal interactions in primary and subharmonic resonant dynamics of imperfect microplates with geometric nonlinearities

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.

Gao's interacting shear flows( ISF) theory and its inferences and their applications

Gao＇s viscous/in-viscid interacting shear flows （ISF） theory, proposed by professor Gao Zhi in Institute of Mechanics, China Academy of Science, and its inferences and their applications in computational fluid dynamics （CFD） are reviewed and some subjects worthy to be studied are pro- posed in this paper. The flow-field and motion law of ISF, mathematics definition of strong viscous shear layer flow in ISF, ISF equations, wall-surface compatibility criteria （Gao＇s criteria ）, space scale variety law of strong viscous shear layer reveals flow mechanism and local space small scale triggered by strong interaction that cause some abnormal severe local pneumatic heating phenomenon in hypersonic flow. Gao＇s ISF theory was used in near wall flow, free ISF flow simulation and design of computing grids, Gao＇s wall-surface criteria were used to verify calculation reliability and accuracy of near wall flows, ISF theory approximate analytical result of shock waves-boundary layer interac- tion and ISF equations were used to obtain the numerical exact solution of local area flow （ such as stationary point flow）. Some new subjects, such as, improving near-wall turbulent models according to the turbulent flow simulation satisfying the wall-criteria and illustrating relation between grid-con- vergence based on the wall criteria and other convergence tactics, are suggested. The necessity of applying Gao＇s ISF theory and wall criteria is revealed. Difficulties and importance of hypersonic vis- cous/in-viscid interaction phenomenon were also emphasized.

用于夹层梁静动力及屈曲分析的新型组合结构单元

推导出新型组合结构单元,用于考虑界面滑移的3层部分作用夹层组合梁的静动力及屈曲特性分析.基于铁木辛柯梁理论,建立考虑夹层梁部分作用效应的能量原理.针对其受力特性,在节点位移、横截面转角和界面滑移插值时均采用含内部自由度的高阶插值函数,以解决含界面有限元数值分析中常遇到的“滑移锁定”现象.通过变分原理得到夹层梁的刚度矩阵、质量矩阵以及几何刚度矩阵的显示表达式.基于MATLAB编译相应夹层结构的有限元程序并验证其准确性.对不同截面3层夹层组合梁进行不同荷载条件和边界条件下的静动力及屈曲特性分析,并探讨不同夹层组合梁跨高比和不同界面抗剪连接刚度下的计算结果及其误差的变化规律.所推导的显示表达式新型组合结构单元计算效率高,并便于推广应用于其他有限元程序或商业软件子程序中.

大跨度高低塔斜拉桥车-桥动力响应

针对大跨度高低塔斜拉桥刚度非对称将导致车-桥空间耦合振动过程更为复杂这一现象,以主跨480 m的高低塔钢箱叠合梁斜拉桥——重庆南纪门长江大桥为工程背景,基于车-桥动力相互作用理论,采用自编程建立车-桥耦合动力模型,分析不同行车模式(列车运行速度、编组数量、运行方向)和高低塔侧刚度差异对车-桥动力响应的影响。结果表明:随着列车运行速度的提高,车-桥系统振动增大;随着列车编组数量的增加,列车振动无明显变化,桥梁振动逐渐增大;桥梁主跨跨中竖向动位移对列车编组数量更敏感,跨中竖向加速度对列车运行速度更敏感;列车运行方向对列车振动影响较小,对桥梁振动则有较大影响;低塔侧主梁各位置处的振动较高塔侧更大。

交互作用分析理论指导下团体心理干预用于肾动态显像检查效果观察

目的探讨交互作用分析理论指导下团体心理干预在肾动态显像检查中的应用效果。方法选取医院2021年8月至2022年12月收治的行肾动态显像检查的患者94例,随机分为观察组与对照组,各47例。对照组患者采取常规护理,观察组患者在此基础上采取交互作用分析理论指导下团体心理干预。结果观察组患者的显像成功率为93.62%,显著高于对照组的78.72%(P<0.05)。干预后,两组患者的抑郁自评量表(SDS)、焦虑自评量表(SAS)评分均显著降低,且观察组显著更低(P<0.05)。观察组患者的护理总满意度为95.74%,显著高于对照组的82.98%(P<0.05)。结论交互作用分析理论指导下团体心理干预应用于肾动态显像检查,可提升显像成功率,缓解患者的抑郁及焦虑情绪,提升满意度。

轮胎动态模型研究的进展

轮胎是汽车唯一接地部件,它提供汽车运动需要的所有驱动、转向和制动力。轮胎力学是汽车动力学的基础。汽车动力学及其控制技术的进一步发展有赖于精确的轮胎动态模型技术。该文综述了轮胎动态模型发展历史与现状,这包括:汽车操稳仿真模型、汽车舒适性仿真模型和汽车疲劳载荷仿真模型。从建模方法的角度,即基于物理的、基于实验的和基于结构的三类方法,对轮胎动态模型的优缺点进行了梳理。可以预计:轮胎动态模型的未来发展将以基于结构的先进轮胎模型为主,与汽车动力学仿真、汽车主动安全系统开发深度融合,并最终走向汽车—轮胎—道路相互作用定量化理论。

创新团队成员知识创新行为的系统动力学研究

提升自主创新能力要求高校必须顺利开展科学研究,因此明确各类影响因素对创新团队成员知识创新行为的作用关系日益受到重视.针对高校创新团队知识创新现状,基于三元交互论、系统动力学理论和流率基本入树法,建立高校创新团队成员知识创新行为的系统动力学模型.对该模型进行管理策略仿真的结果表明:对创新团队成员个体所处环境的创新氛围和人际信任关系进行管理,更有利于提升个体知识创新力、促进团队长远发展与知识生产.

锚泊多浮体系统动态响应

为保证锚泊多浮体系统能够在波浪中正常作业和生存,基于三维频域G reen函数法就一定水深不同浪向下锚泊多浮体系统的运动响应、锚缆拉力和连接器载荷进行了数值预报。分析中考虑到了浮体辐射势之间的相互影响以及连接器和锚系对于浮体运动响应的影响。分析表明,浮体的运动响应、连接器载荷以及锚缆张力受波频和浪向的影响很大,各项的极值出现在低频范围,浪向在30°和45°之间,连接器载荷出现最大值,而锚缆张力则在浪向90°时张力最大,处于迎浪面的锚缆张力较大于处于背浪面的锚缆张力。

土-结构相互作用对消能减震结构动力特性的影响

基于系统化的集总数模型来表示土体的动力特性,建立土-消能减震结构相互作用体系的运动方程,采用复模态理论研究2个关键参数(土体剪切波速、结构高度与基础特征宽度的比值)对不同周期、不同阻尼比的减震结构动力特性的影响。研究表明:考虑土-结构相互作用后,非减震结构体系随着土体剪切波速的下降会加大整个体系的第一模态阻尼比;对于减震结构比,体系随着土体剪切波速的下降会削弱整个体系的阻尼比,且减震结构阻尼比越大,其削弱程度越明显。因此与普通结构相比,减震结构更需要考虑土-结构相互作用效应对其产生的不利影响。

迁移观的演进及测评范式的变革

当前的迁移理论试图将认知因素与情境因素加以融合,强调在情境中、尤其是在社会文化情境中主动迁移抽象的符号表征,强调迁移过程中头脑内部的认知表征与外部情境因素间的相互作用。迁移的内涵不再是回忆或直接应用习得的已有经验,而是人境互动过程中的动态建构与生成。迁移是评价学习成效的核心指标之一,其内涵的演变必将引发测评范式的变革。迁移测评从记忆水平的单一"迁出"范式转向建构应用水平的"迁出"与"迁入"兼顾的双重测评范式,后者更为强调生态效度及多维测评指标体系的选定,更侧重考察可持续发展的学习能力。

重大基础设施工程技术决策风险因素作用机理研究

重大基础设施工程是特定的技术集成体和现实生产力的基础,技术决策是其建设管理的核心,存在技术集成复杂、环境动态多变、不确定因素多等问题,易引发不可逆的风险事故,技术决策风险的有效识别和控制事关决策能否成功。基于扎根理论,建立包含3个风险类别、13个一级风险因子和42个二级风险因子的重大基础设施工程技术决策风险指标体系,并运用熵权法求得指标权重;通过风险因素关系分析,构建基于系统动力学的因果关系图,揭示重大基础设施工程技术决策风险因素的动力机制和作用机理。研究发现,重大基础设施工程技术决策风险是在环境风险因素、决策制定过程和决策执行过程风险因素的共同作用下产生的,其中,环境风险不受其他2类风险因素影响,而环境风险易催发决策制定过程风险与决策执行过程风险,此外,决策制定过程风险与决策执行过程风险的权重相对较高,表明二者对重大基础设施工程技术决策风险影响较大。研究结果可为重大工程技术决策的风险识别和控制提供依据。

基于轮轨线性相互作用假定的车桥相互作用理论及应用

研究车桥耦合系统中轮轨相互作用关系问题。以刚体动力学方法建立车辆子系统模型,有限元法建立桥梁子系统模型;假定车辆轮对与钢轨之间在竖向上服从轮轨密贴假定,在横向上服从Kalker蠕滑理论;并在计算横向蠕滑力时考虑轮对锥形踏面和恒定法向力;以轨道不平顺为系统激励;建立车辆-桥梁统一的线性动力平衡方程组。利用上述轮轨线性相互作用假定,以SS8单节机车通过单跨32m简支梁为例,计算各轮对横向运动的时域及频域响应;讨论轮对蛇形运动波长、波幅的影响因素;分析桥梁横向振动、横向轨道不平顺以及车辆系统横向振动三者的关系;并验证轮对蛇行波假定的正确性。

绝对空间中的铁道车辆非线性动力学仿真

从铁道车辆三维可视化建模和仿真要求出发,基于面向对象软件技术,本文叙述了绝对空间中铁道车辆非线性动力学仿真的有关力学原理和计算结构,特别是Hertz理论在空间轮轨弹性碰撞中的完整应用。并用编制的仿真软件VSDS对ManchesterBenchmarks的客车模型进行了曲线通过工况仿真,指出绝对空间中铁道车辆非线性动力学仿真的可行性和实用性。