故障录波装置在电力牵引网的应用

介绍了一种能够满足电力牵引网特殊要求的通用型故障录波装置,该装置能区分电力牵引网和普通电力系统输电线路故障,并具有故障测距和电能质量分析和记录功能。文章对装置的硬件结构、算法和主要功能、技术指标等作了分析。     

青岛液体化工码头工程潮流数值模拟分析

通过潮流的数值模拟 ,从流的角度对青岛港液体化工码头拟建工程的 4个方案进行了研究分析和评价。由此得出 ,方案 1船舶靠离条件最好 ;突堤端部不同堤长对流场影响不大 ;且对一期油码头的船舶靠离有利     

基于抽样车辆轨迹数据的信号控制交叉口排队长度分布估计

排队长度是评价信号控制交叉口运行状态的重要参数之一。现有大多数基于抽样车辆轨迹数据的排队长度估计方法可以实现周期级排队长度估计，但是需要信号配时、渗透率或车辆到达分布等实践中难以获取的输入信息。此外，这类方法在低渗透率条件下往往难以确保估计结果的准确性和可靠性，极大地限制了其实用性。因此，提出一种抽样车辆轨迹数据驱动的时段级信号控制交叉口排队长度分布估计方法，可不依赖任何交通流理论模型和前述输入信息实现排队估计。首先，通过理论推导可以证明时段内抽样车辆的停车位置分布和排队长度分布之间可互相转化；然后，提出一种扩展的核密度估计方法来拟合并平滑抽样车辆停车位置分布，从而有效地适应不同日期和周期的轨迹叠加所带来的波动，提高方法的适用性；最后，基于前述推导和拟合的停车位置分布实现时段排队长度分布、平均排队长度和百分位排队长度估计。分别采用仿真和实证数据对上述方法进行验证和评价。结果表明，通过叠加5 d相同时段的抽样轨迹数据，15 min的平均排队长度估计误差仅为1.59 veh，相对误差仅为9%。同时，面向不同分析时长，只要给定超过100 veh抽样车辆的观测样本，无论渗透率高低，所提出的方法在定时或自适应信号控制交叉口都可实现时段排队长度分布的准确估计，其成果可进一步用于信号控制交叉口运行可靠性评估以及多时段定时信号控制的鲁棒优化。     

城市轨道交通列车运行噪声估算方法探讨

列车运行噪声是高架线路声屏障、地下线路活塞风井消声器的设计输入条件。通过列车运行噪声影响因素分析,建立了列车运行噪声估算的简化模型,推导了城市轨道交通列车在不同运行条件、不同运行速度时的运行噪声估算方法。     

基于扩展卡尔曼滤波的轨道垂向不平顺估计

轨道不平顺是影响列车平稳性和舒适度的关键因素,因此及时掌握线路状态对保证列车的运行安全具有重要意义。针对采用单个惯性量较难达到对不同波段不平顺的检测,通过观测多个惯性量,运用扩展卡尔曼滤波解决非线性离散系统的最优估计原理,根据车辆轨道耦合状态空间方程计算递推雅克比矩阵,并结合线性观测方程得到最优状态估计,实现轨道不平顺估计。在Matlab平台下,进行了实测轨道不平顺激励作用下的仿真,将仿真得到的观测值采用本文提出的方法进行轨道垂向不平顺估计,结果表明该算法具有很好的精确性。     

Lateral load transfer and normal forces estimation for vehicle safety: experimental test

Knowledge of vehicle dynamics data is important for vehicle control systems that aim to enhance vehicle handling and passenger safety. This study introduces observers that estimate lateral load transfer and wheel–ground contact normal forces, commonly known as vertical forces. The proposed method is based on the dynamic response of a vehicle instrumented with cheap and currently available standard sensors. The estimation process is separated into three blocks: the first block serves to identify the vehicle’s mass, the second block contains a linear observer whose main role is to estimate the roll angle and the one-side lateral transfer load, while in the third block we compare linear and nonlinear models for the estimation of four wheel vertical forces. The different observers are based on a prediction/estimation filter. The performance of this concept is tested and compared with real experimental data acquired using the INRETS-MA (Institut National de Recherche sur les Transports et leur Sécurité – Département Mécanismes d’Accidents) Laboratory car. Experimental results demonstrate the ability of this approach to provide accurate estimation, thus showing its potential as a practical low-cost solution for calculating normal forces.     

江都散货泊位船舶操纵仿真模拟研究

拟建江都散货泊位工程水域附近流态复杂。为保证进出港船舶和靠、离泊作业船舶的安全,需要对拟建工程进行模拟仿真研究。根据实地拍摄视景图片和定位,制作出码头附近的三维视景库,利用当地实测地形资料和相关资料,制作出包括码头设计尺寸、航道的三维地形图和视景图及电子江图,运用水流模拟软件进行模拟和验证,建立了6自由度的设计船舶模型,根据不同风、流组合条件,进行了模拟航行和操纵试验,得到试验数据和模拟研究结论。本次模拟研究,首次使用专业水流模拟软件,结合大型船舶操纵模拟器进行试验,使结果更加具有参考价值和科学依据。     

Robust road friction estimation during vehicle steering

Automated vehicles require information on the current road condition, i.e. the tyre–road friction coefficient for trajectory planning, braking or steering interventions. In this work, we propose a framework to estimate the road friction coefficient with stability and robustness guarantee using total aligning torque in vehicle front axle during steering. We first adopt a novel strategy to estimate the front axle lateral force which performs better than the classical unknown input observer. Then, combined with an indirect measurement based on estimated total aligning torque and front axle lateral force, a non-linear adaptive observer is designed to estimate road friction coefficient with stability guarantee. To increase the robustness of the estimation result, criteria are proposed to decide when to update the estimated road conditions. Simulations and experiments under various road conditions validate the proposed framework and demonstrate its advantage in stability by comparing it with the method utilising the wide-spread Extended Kalman Filter.     

基于OD反推模型预测客运通道客流量

OD矩阵是进行客流预测的重要基础数据,在实际操作过程中,获取吸引区之间的OD矩阵却是非常困难的,一般采用OD调查的方式,但缺陷是调查过程较为费时、费力。本文提出一种免OD调查,利用客流区段观测值直接反推OD矩阵的方法。首先讨论了传统"四阶段"模式与OD反推预测模式的联系和区别,然后阐述以重力模型为结构的基于区段客流量反推OD矩阵模型,并利用最大似然法对模型参数进行迭代求解,最后结合一个具体实例,运用该方法对武广客运通道的客流量进行了预测分析,采用试算法模拟重力模型的参数,误差控制良好,结果验证了方法的有效性。     

Determinants of the property damage costs of tanker accidents

This study investigates determinants of the vessel, oil cargo spillage, and other-property damage costs of tanker accidents. Tobit estimation of a three-equation recursive model suggests that, among types of tanker accidents, fire/explosion accidents incur the largest vessel damage costs, but the smallest oil cargo spillage costs. Alternatively, grounding accidents incur the smallest vessel damage costs, but the largest oil cargo spillage costs, reflecting the difficulty of controlling oil cargo spillage subsequent to such accidents. Also, oil cargo spillage costs are lower for US flag tanker accidents. A dollar of vessel damage cost increases other-property damage cost by $0.06, whereas a dollar of oil cargo spillage increases this cost by $1.55.