尾轴架结构设计

尾轴架设计的好坏直接影响整个船体尾部工作状态及推进效率,而制约尾轴架设计的客观因素有很多。以某工作船为研究对象,详细介绍了尾轴架结构设计特点及其外载荷的计算方法。通过有限元模拟,分别考察和探讨了支臂的数量、支臂间夹角及支臂的剖面形状等几个方面对尾轴架强度和刚度的影响,并得出了一些结论及建议。     

Short‐term traffic flow prediction with linear conditional Gaussian Bayesian network

Traffic flow prediction is an essential part of intelligent transportation systems (ITS). Most of the previous traffic flow prediction work treated traffic flow as a time series process only, ignoring the spatial relationship from the upstream flows or the correlation with other traffic attributes like speed and density. In this paper, we utilize a linear conditional Gaussian (LCG) Bayesian network (BN) model to consider both spatial and temporal dimensions of traffic as well as speed information for short‐term traffic flow prediction. The LCG BN allows both continuous and discrete variables, which enables the consideration of categorical variables in traffic flow prediction. A microscopic traffic simulation dataset is used to test the performance of the proposed model compared to other popular approaches under different predicting time intervals. In addition, the authors investigate the importance of spatial data and speed data in flow prediction by comparing models with different levels of information. The results indicate that the prediction accuracy will increase significantly when both spatial data and speed data are included. Copyright © 2016 John Wiley & Sons, Ltd.     

A G/G(n)/C/C state‐dependent simulation model for metro station corridor width design

Metro station corridor and passengers are described as a G/G(n)/C/C state‐dependent queuing system with a general random arrival interval G and a general random and state‐dependent service time G(n) to offset the shortcomings in existing design methods. The corresponding G/G(n)/C/C state‐dependent discrete event simulation model is developed, and its high‐fidelity is tested. Then the optimization algorithm based on the simulation model is designed to determine corridor width. The proposed simulation optimization method and the existing analytical optimization methods, based on M/G(n)/C/C and D/D/1/C queuing models, are applied to design corridor width in a numerical example of 48 combinations of passenger flow rates and level of service (LOS). The designed corridor widths are tested in a micro‐simulation model, and the performance measure is compared. The result shows that the corridor widths obtained by the new method are 0.357 m (7.4%) larger than that of the other two methods on average; the area per passenger of the new method increases 10.53% and 11.63%, respectively, compared with that of the other two methods; the widths designed by the new method satisfy the requirement of LOS under various passenger flows, whereas 93% of the corridor widths obtained by the other two methods fail to meet the requirement of LOS, and the corridor widths designed by the new method have high elasticity coefficients of LOS‐width. Copyright © 2015 John Wiley & Sons, Ltd.     

大跨度波形钢腹板梁桥施工线形分析研究

针对大跨度波形钢腹板施工控制困难,结构复杂,温度敏感,施工要求严格,施工控制难度大,技术应用缺乏有效借鉴等不利因素,以我国在建的广东某大桥工程为背景,系统研究了波纹钢腹板PC梁桥施工全过程线形变化过程。通过现场实测和理论计算对比分析线形、应力监测与调整方法,总结出影响施工控制的主要因素和有效措施,为今后类似桥梁设计提供参考价值。     

绞吸挖泥船横移过程二次型最优控制

在疏浚作业过程中,挖泥船主要的作业参数是由操作人员根据自己的经验、试挖情况以及挖泥船实际作业效果灵活确定的,而疏浚操作人员的经验和理论水平也相差较大,所以手动作业的实际产量要远远低于预计产量,效率低下,作业成本偏高,作业质量较差。为了克服该缺点,本文提出了一种基于疏浚系统状态空间模型的线性二次型最优控制策略,并设计了最优控制跟踪器应用于绞吸挖泥船横移过程的控制中,该跟踪器是智能控制替代人工操作的一种有效方法。文中对应用二次型最优控制策略的效果进行了MATLAB仿真分析,仿真结果表明：采用了二次型最优控制策略后,系统稳定、响应快、滞后小,对期望输出的跟踪性好,可以应用于挖泥船疏浚作业过程中。     

主动前轮转向控制技术的现状与发展趋势

文章在介绍两种主动前轮转向系统工作原理的基础上,从车辆动力学控制的角度,详细总结和分析了各种用于主动前轮转向的控制方法,包括横摆角速度控制、D*控制、侧倾稳定性控制和变转向传动比控制等。并指出在未来的主动前轮转向控制研究中,集成控制将是发展的必然方向。     

北美汽车工业的演变

分析北美自由贸易协议的演变,检验WTO多边贸易体制的影响,以加拿大汽车工业为例,为贸易规则试图对汽车工业的影响提供概述,对中国汽车工业的发展及其在多边贸易体制中的运作有一定的启发和借鉴。     

瞬态瑞雷波法在地基固结效果检测中的应用

基于软土固结中剪切波速增值与固结度的关系理论,介绍了将瑞雷波测试技术与室内土工试验成果相结合,检测分析软土地基固结效果的方法.将该检测方法应用于路基工程中,并与原位孔隙水压力监测成果对比分析,说明该方法是可靠的.     

小桥涵自由出流出口抛石防护试验

通过小桥涵自由出流出口抛石冲刷试验得出:抛石粒径、抛石长度适当,抛石与床沙形成复合冲坑,抛石覆盖坑底,具有良好的减冲效果;提出对其控制条件和有关冲刷防护计算方法.     

基于模糊C均值聚类的模拟电路故障诊断

介绍了模糊C均值聚类分析的理论,并将该理论应用于模拟电路故障诊断.在模拟电路故障仿真分析中引入有容差的各类数据样本,运用迭代优化的模糊聚类算法生成故障模式,然后,将故障模式应用于未知故障情形进行诊断,仿真表明,该方法高效准确.