散粮输送工艺设备分析

通过对散粮输送行业中常见的工艺设备进行探究,分析设备运行过程中可能存在的问题,提出合理的解决方案,为散粮系统工艺设计及工程运行提供重要参考意义。     

A design method of tensile triangles and low transformation temperature weld metal for reduction of stress concentration and residual stress of welded joints

Stress concentration and residual stress have a significant influence on fatigue life of welded joints. In order to reduce the stress concentration of welded joints, a mathematical design method of tensile triangles (MTT) based on bionics was applied to weld shape design. Accordingly, the stress concentration of various weld beads in the corner boxing welded joint and the fillet welded T-joint was dissected using our in-house FEM software JWRIAN. It was found that there existed a large stress concentration in the conventional welded joints, whereas those welded joints with elongated weld bead were accompanied by a lower stress concentration, especially for elongated weld bead with MTT design. Furthermore, among the weld shapes of the corner boxing fillet welded joint, the rectangle shape of weld bead had the minimum stress concentration factor (1.05). For the fillet welded T-joint with MTT design, the stress concentration of weld toe decreased dramatically with the increase of the index of designed shape, but there was a minor difference of stress concentration at weld root between the weld beads with MTT design. In addition, application of low transformation temperature (LTT) weld metal utilizing martensitic transformation to the fillet welded T-joints can produce compressive residual stress at weld toe.     

浅谈信号系统侧冲防护在城市轨道交通中的应用

防侧面冲突是信号系统最基本的安全功能之一,城市轨道交通信号系统如何在兼顾安全与效率的前提下进行侧冲防护,对整个信号系统的设计尤为重要.本文重点介绍了侧冲防护的原则及其防护原理.     

Impact assessment of extreme weather events on transport networks: A data-driven approach

The present paper presents a data-driven method for assessing the resilience of the European passenger transport network during extreme weather events. The method aims to fill in the gap of current research efforts regarding the quantification of impacts attributed to climate change and the identification of substitutability opportunities between transport modes in case of extreme weather events (EWE). The proposed method consists of three steps concerning the probability estimation of an EWE occurring within a transportation network, the assessment of its impacts and the passengers’ flow shift between various transport modes. A mathematical formulation for the proposed data-driven method is provided and applied in an indicative European small-scale network, in order to assess the impacts of EWE on modal choice. Results are expressed in passenger differentiated flows and the paper concludes with future research steps and directions.     

兰州地铁地温分布特性及其演化规律

以兰州地铁所在地区为研究对象,实测地铁隧道开挖前的地温(简称为初始地温),根据实测数据,提出地铁初始地温预测模型公式。采用非稳态传热的数值模型,分析运营条件下地铁隧道围岩温度的演化规律。结果表明:兰州地铁初始地温随环境气温和埋深的变化而变化;年变温层位于自地表至埋深12m处;年恒温层位于埋深12m及其以下,温度为15℃左右;年变温层中,1年内初始地温变化规律与环境气温变化规律相似,近似呈正弦曲线状分布,但存在相位滞后的现象;1年中初始地温的振幅随埋深的增大呈指数下降趋势。在隧道内空气与围岩之间热交换中,兰州地铁隧道围岩的温度及其梯度、热透厚度(未达到极限时)均与隧道内环境温度、热交换时间成正相关关系,但与距隧道内壁的距离成负相关关系。     

共享停车泊位数量可变下交通流逐日演化规律

为了揭示在共享停车泊位数量可变条件下的网络交通流逐日演化规律,首先构建了共享泊位交易系统,并考虑了交易市场中的共享泊位提供者可以选择2种异质性的价格预期方式,即理性预期方式和幼稚预期方式;而后对共享泊位的均衡价格、2种提供者的占比差、高峰时段公交和小汽车需求的演化规律进行了分析;其次,以2条平行路径的路网为例,对网络交通流量分配的最终演化结果进行了分析;最后,在对上述2个系统的最终演化状态给出定量判据后,以北京市实际路网为例进行了数值试验。理论分析和数值试验结果表明:①对于共享泊位交易系统,若供给曲线斜率小于需求曲线斜率,则共享泊位交易系统的唯一均衡解可实现无条件渐进稳定;否则若理性提供者的交易与预测成本之和大于幼稚提供者,则存在临界提供者选择强度,使得共享泊位交易系统在大于此临界值条件下出现分岔或混沌现象;②对于网络交通流系统,若出行成本对路径流量敏感度小,路径选择概率对出行成本敏感度小,小汽车需求量不大,则系统唯一的均衡解可能是渐进稳定的,否则系统会出现分岔或混沌状态;③当共享泊位交易系统处于渐进稳定状态时,若提供者对共享泊位的价格变动不敏感,用户对其价格变动敏感,潜在共享泊位需求量不大,理性提供者的交易与预测成本之和并非远大于幼稚提供者,提供者选择强度不大,则由于受到共享泊位交易总量的限制,高峰时段的均衡小汽车需求不大,导致网络交通流系统的最终演化状态容易趋向于渐进稳定;④当共享泊位交易系统处于混沌状态时,网络交通流系统会产生更加严重的分岔与混沌现象。     

道路环境对交通安全的影响及对策

交通安全,涉及到人、车以及道路和环境等很多因素。近年来,因为各种原因使得有关单位以及人员将更多的将精力放在人、车、道路这几个因素上,对道路交通环境没有过多的考虑和研究。深入研究道路交通环境,有利于道路交通的安全,文章通过对其的研究和分析,得出有关道路交通环境对交通安全的影响和解决措施,对于防止道路交通安全事故具有重要意义。同时为人们的生命财产的安全提供保障、对构建社会主义和谐社会具有很大帮助。     

Competitiveness of container terminal operating companies in South Korea and the industry–university–government network

Burgeoning container port facilities have fostered intensified competition among container terminal operating companies (CTOCs). However, despite research into their survival strategies which identified antecedents of competitiveness including hard factors such as facilities, available cargo and cargo processing ability, softer factors spanning human resource management, networks and strategic alliances with universities and government agencies in industry–university–government (I–U–G) networks have been overlooked. This study aims to examine both hard and softer antecedents of competitiveness as perceived by 152 professionals in South Korean CTOCs; empirical relationships among these antecedents, I–U–G networks, and competitiveness itself; and the significance of the I–U–G network in establishing and improving competitiveness. Posited antecedents of competitiveness included human resources, facilities, service quality, customer orientation, reputation, and government support policy as independent variables; the I–U–G network as a moderating variable; and competitiveness as a dependent variable. Empirical structural relationships revealed that excepting government support policy, each variable significantly affected CTOC competitiveness. Further, the I–U–G network moderated the relationships between the antecedents of competitiveness and competitiveness. Because an effective I–U–G network was pivotal in controlling CTOC competitiveness, improved competitiveness requires not only differentiation of human resources, facilities, service quality, customer orientation, and reputation factors but also I–U–G network developments.     

成昆铁路矮塔斜拉桥索梁锚固区模型试验研究北大核心

为研究铁路矮塔斜拉桥索梁锚固区的受力形式,以成昆铁路金沙江大桥为工程背景,针对该桥采用的新型梁顶混凝土锚固构造,通过缩尺模型试验研究其在不同荷载下的应力分布和开裂特征。结果表明:在斜拉桥成桥恒载索力作用以及最不利荷载组合索力作用下,C7锚固块更容易发生破坏,将其作为试验构件开展缩尺模型试验,发现锚固块在不同张拉荷载作用下张拉至设计索力的过程中,应变增幅基本上线性增加,卸载后同样呈线性减小,说明混凝土受力处在线弹性阶段,且应力在规范要求范围内。在试验荷载加载至140%设计索力时,锚固块前端倒角位置开始出现细小裂纹且随荷载的增加不断开展。当荷载卸载至0时,之前出现的裂缝随荷载的减小逐渐闭合,宽度肉眼不可见,表明该构造能够满足正常使用要求且具备足够的安全储备。     

车务可视化信息系统设计与实现

车务可视化信息系统通过三维模型及虚拟漫游的展现形式,将铁路运行及运营的动态信息进行集成和柔性展示,实现旅客服务信息及运输管理相关数据的整合,通过可视化的展现方式既方便旅客及管理人员,又充分展示铁路信息化建设的成果。