A new model for temporal–spatial stochastic analysis of vehicle–track coupled systems

The vehicle–track coupled system has a random nature in the time–space domain. This paper proposes a computational model to analyse the temporal–spatial stochastic vibrations of vehicle–track systems, where the vehicle–track system is divided into a vehicle subsystem, track subsystem, and interfacial subsystem between the wheel and rail. In this model, the time-varying randomicity of dynamical parameters of the vehicle system, correlation, and randomness of the track structural parameters in the time–space joint dimensions, and randomness of the track random irregularities are considered. A probability dimension-reduction method was used to randomly combine different random variables. Furthermore, the probability density evolution method was applied to solve the delivery problem of probabilities between excitation inputs and response outputs. The temporal–spatial stochastic vibrations of the vehicle–track system with different coefficients of variation were studied, in which we assumed that the dynamic parameters obeyed the normal distribution, and the stochastic simulation method of the track random irregularities is probed into. The calculated results from this model are consistent with the actual measured results and physical conceptions. Thus, the temporal–spatial stochastic evolutionary mechanism can be explored, and the limits of dynamic indices can be formulated by using this developed model.     

Direct yaw moment control and power consumption of in-wheel motor vehicle in steady-state turning

Driving force distribution control is one of the characteristic performance aspects of in-wheel motor vehicles and various methods have been developed to control direct yaw moment while turning. However, while these controls significantly enhance vehicle dynamic performance, the additional power required to control vehicle motion still remains to be clarified. This paper constructed new formulae of the mechanism by which direct yaw moment alters the cornering resistance and mechanical power of all wheels based on a simple bicycle model, including the electric loss of the motors and the inverters. These formulation results were validated by an actual test vehicle equipped with in-wheel motors in steady-state turning. The validated theory was also applied to a comparison of several different driving force distribution mechanisms from the standpoint of innate mechanical power.     

Insights into vehicle trajectories at the handling limits: analysing open data from race car drivers

Race car drivers can offer insights into vehicle control during extreme manoeuvres; however, little data from race teams is publicly available for analysis. The Revs Program at Stanford has built a collection of vehicle dynamics data acquired from vintage race cars during live racing events with the intent of making this database publicly available for future analysis. This paper discusses the data acquisition, post-processing, and storage methods used to generate the database. An analysis of available data quantifies the repeatability of professional race car driver performance by examining the statistical dispersion of their driven paths. Certain map features, such as sections with high path curvature, consistently corresponded to local minima in path dispersion, quantifying the qualitative concept that drivers anchor their racing lines at specific locations around the track. A case study explores how two professional drivers employ distinct driving styles to achieve similar lap times, supporting the idea that driving at the limits allows a family of solutions in terms of paths and speed that can be adapted based on specific spatial, temporal, or other constraints and objectives.     

双车道公路危险路段评价指标与安全改善对策

选取相邻路段车速差△V、车速降低系数SRC和速度离差作为鉴别双车道公路危险路段的三个评价指标,从道路工程措施和交通安全设施两方面对事故多发路段进行安全改善对策研究。以内蒙古S203公路为例,利用评价指标进行危险路段判析,针对K465＋900急弯陡坡危险路段,通过线形改造以及设置交通标志标线、减速设施、避险车道和防护设施等一系列工程改造措施,进行安全改善综合方案设计。     

互通立交平面线形设计的经验探讨

通过设计工作的实践,探讨互通立交平面线形设计的具体步骤、操作方法和注意事项,并对匝道线元参数的取值、线元参数与运行速度的关系、线形设计的连续性与协调性等方面提出了一些见解。     

湖北城际铁路动车组选型与交路优化研究

以湖北城际铁路为例,通过比照区间运行速度、参考我国高级动车的技术配置合理选择车型,并优化原交路,最终对原、现两种方案的成本效益对比分析,实证表明,该方案有助于减少动车购置成本,降低亏损,并简化原有运输组织工作.     

基于物联网技术的高速铁路综合维修物流监控系统

提出了基于物联网技术的高速铁路综合维修物流作业管理流程及监控系统组成,并对该系统实现的关键技术问题即多阅读器碰撞问题进行了Matlab仿真实验和现场试验,研究结果表明利用概率功率控制算法的阅读器,在阅读器5台以下的情况,高铁综合维修物流监控系统多阅读器可利用嵌入式软件监控范围超过3.5 m,可达到比较理想的状态,保证了该系统实现的可行性.     

高速铁路声屏障在列车脉动风载荷下的强度计算

为了得到高速列车声屏障在列车经过时的受力规律,建立了声屏障的外流场模型和有限元模型。利用流固耦合技术,计算分析了声屏障的三维动态流场和结构模型,得到了列车风气动力特性和H钢立柱的受力规律。计算结果表明:列车经过时声屏障受到的压力为一个随时间变化且不均匀分布的面载荷。H钢立柱发生弯扭组合变形,弯矩扭矩各经历两次换向。每当列车经过一次,等效应力产生四个脉冲。H钢立柱受到的应力不大,可能出现疲劳破坏。     

叶片数对喷水推进低比转速轴流泵叶轮水动力性能的影响

喷水推进低比转速轴流泵是随着喷水推进技术的发展而产生的一种新泵型。针对一型低比转速轴流泵叶轮叶片数分别选取为5、6、7建立三组叶轮模型,选择RNG k-ε两方程涡粘模型进行叶轮内流场与功率、总压扬程、效率的数值模拟计算,得到三组叶轮的相关水动力曲线。在此基础上分析叶片数对低比转速轴流泵叶轮水动力性能的影响,得到叶片数对功率、总压扬程与工况点影响较大,而基本不影响最高效率的结论,为我国该类泵型的深入研究提供参考。