Sliding window method for vehicles moving on a long track

The rail is modelled as a simply supported beam in the vehicle–track coupled dynamics. The beam is formulated by a partial differential equation that is transformed into an ordinary differential equation by the method of mode superposition for numerical calculation. However, the size of the matrix that is formed by the mode-superposition method increases significantly with track length, which limits the calculation efficiency. Some methods have been developed to solve this calculation issue, but they diminish the merits of the vehicle–track coupled dynamics, which would systematically investigate the dynamics of a vehicle and a track from the entire vehicle–track system. A new method is developed to resolve this contradiction. First, a theory based on a sliding window is established to improve the computational stability with respect to the length and the window-movement ratio. Then, two methods, namely finite element method analysis and an analytical solution, are used to verify the accuracy of the new method, which is highly efficient when used in a vertical half-vehicle–track coupled model to calculate the vehicle response when the vehicle moves on a long track. The results of the vehicle response calculated with and without the sliding window show good consistency.     

Measurements of car-body lateral vibration induced by high-speed trains negotiating complex terrain sections under strong wind conditions

Assessment of the vibration of high-speed trains negotiating complex sections of terrain under strong wind conditions is very important for research into the operation safety and comfort of passengers on high-speed trains. To assess the vibration of high-speed trains negotiating complex sections of terrain under strong wind conditions, we performed a field measurement when the train passes through typical sections of complex terrain along the Lanzhou–Xinjiang high-speed railway in China. We selected the lateral vibration conditions, including the roll angle and lateral displacement of car-body gravity centre through two typical representative sections (embankment–tunnel–embankment and embankment–rectangular transition–cutting) for analysis. The results show that the severe car-swaying phenomenon occurs when the high-speed train moves through the test section, and the car-body lateral vibration characteristic is related significantly to the state of the terrain and topography along the railway. The main causes for this car-swaying phenomenon may be the transitions between different windproof structures, and the greater the scale of the transition region between different windproof structures or landform changes, the more obvious the car-swaying phenomenon becomes. The lateral vibration of the car-body is relatively steady when the train is running through terrain with minor changes in topography, such as the windbreak installed on the bridge and embankment, but the tail car sways more violently than the head car. When the vehicle runs from the windbreak installed on the embankment into the tunnel (or in the opposite direction), the tail car sways more intensely than the head car, and the head car runs relatively stable in the tunnel.     

A stochastic analysis of highway capacity: Empirical evidence and implications

This paper presents a stochastic characterization of highway capacity and explores its implications on ramp metering control at the corridor level. The stochastic variation of highway capacity is captured through a Space–Time Autoregressive Integrated Moving Average (STARIMA) model. It is identified following a Seasonal STARIMA model (0, 0, 2₃) × (0, 1, 0)₂, which indicates that the capacities of adjacent locations are spatially–temporally correlated. Hourly capacity patterns further verify the stochastic nature of highway capacity. The goal of this paper is to study (1) how to take advantage of the extra information, such as capacity variation, and (2) what benefits can be gained from stochastic capacity modeling. The implication of stochastic capacity is investigated through a ramp metering case study. A mean–standard deviation formulation of capacity is proposed to achieve the trade-off between traffic operation efficiency and robustness. Following that, a modified stochastic capacity-constraint ZONE ramp metering scheme embedded cell transmission model algorithm is introduced. The numerical experiment suggests that considering capacity variation information would alleviate the spillback effect and improve throughput. Monte Carlo simulation further supports this argument. This study helps verify and characterize the stochastic nature of capacity, validates the benefits of using capacity variation information, and thus enhances the necessity of implementing stochastic capacity in traffic operation.     

载货车悬置系统优化分析及改进

针对公司某款中型载货车发动机悬置隔振效果差的问题,提出了相对应的解决方案。根据现有车辆实验测定的振动数据和现有软垫的刚度参数,优化悬置系统的参数,应用ADAMS软件的分析优化,并通过振动试验的测定,最终达到优化悬置隔振的目标。为以后的载货车的悬置优化分析计算提供参考依据。     

基于Digatron电池测试系统的锂电池温度寿命试验技术研究

本文主要论述了利用目前国际主流的Digatron电池测试分析系统,选取温度作为表征锂电池组寿命特性的参数,设计了电池组性能试验,通过实验数据分析得到了锂电池组寿命特性趋势,对于改善车辆电池控制管理策略具有指导意义。     

基于Peck公式的藏区公路隧道施工地面沉降预测

在隧道施工中结合现场地表下沉量测实测数据,利用Peck公式进行地表沉降计算,反分析法确定沉降槽曲线最大沉降量和沉降槽宽度及关键参数,并对拟合参数进行了检验。比较修正了沉降槽宽度计算经验公式,给出青藏高原东南部地区Peck公式中沉降槽宽度系数的初步建议值,验证了适合我国藏区具体地质条件与施工手段的公路隧道地表沉降预测模型。研究表明:Peck公式适用于青藏高原地区公路山岭隧道施工地面沉降预测,隧道进口浅埋段施工引起的地表沉降曲线基本符合高斯分布规律,进口段埋深较浅地表沉降槽宽度越大,埋深越大沉降槽宽度越小。     

基于手机信令数据的游客识别与出行轨迹匹配方法

为统计旅游交通的客运量，分析公路交通运输需求，优化运输组织，合理构建“快进慢游”综合交通旅游网络，研究提出基于手机信令数据的游客识别与出行轨迹匹配方法。通过划定景区边界，设置停留时间阈值，识别手机用户的游客身份；同时，借助地图工具批量计算信令发生位置间的出行路线与行程时间，匹配实际公路网。实例分析结果表明，手机信令数据能呈现手机用户的出行轨迹，且信令数据的位置轨迹与公路线位走向结合密切。在人们越来越依赖地图导航软件规划出行路径的背景下，利用该方法能更准确地识别景区游客并估计游客往来景区的出行路径。     

复杂线型地铁盾构隧道开挖引起的地表位移预测

将地铁隧道施工引起的地表移动视为随机过程,应用随机介质理论对具有坡度的地铁隧道地表位移公式进行了推导,并提出了曲线型地铁隧道地表位移的修正公式。同时结合坐标变换理论,对复杂线型下的地表位移曲面进行了分析。以此为理论基础编制了计算程序,计算表明,该程序可以计算复杂线型下的地表位移曲面。这对于预测多条复杂线型隧道下的地表空间位移曲面来说具有重要意义。     

DF4型内燃机车喷油器针阀偶件损坏的原因及防止措施

根据现场实际对 DF_4型内燃机车喷油器的针阀偶件损坏原因进行分析,总结出一套防止喷油器的针阀偶件损坏的方法。     

大型编组站驼峰峰高计算参数取值的探讨

本文主要以武汉北编组站为例，介绍了大型编组站驼峰峰高计算方面有关参数的取值改进方法的个人见解，使驼峰峰高计算在满足设计规范的基础上更符合实际。