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1. chinaXiv:202010.00078 [pdf]

BDSP2020.pdf

孔云峰
Subjects: Traffic and Transportation Engineering >> Traffic and Transportation System Engineering

针对我国城市公交企业生产作业计划编制的需求,设计了一个公交车辆与司机调度问题的通用算法。算法支持电动车辆调度,适用于单线或跨线运营管理,满足人车固定或人车分离的调度模式,也支持灵活的车辆与司机相关参数设置。问题目标包括车辆固定成本、车辆行驶成本、司机固定成本和司机津贴成本,约束条件包括最短停车时间、电动车辆续航里程及充电时间、司机休息与就餐等。算法框架中包含案例数据管理、问题定义、初始解生成、局部搜索算子、搜索策略、数学建模等基本模块,方便于常见优化算法的实现。使用62个单线案例和11个跨线案例进行算法测试,并比较了不同运营模式下调度结果的差异。测试结果验证了算法的功能和性能,案例结果比较发现:使用续航里程150km电动车辆取代燃油车辆,单线运营车辆数量增幅为0.8%,跨线运营增幅为1.6%;与单线运营相比,跨线运营所需车辆和司机数量分别减少4.6%和2.4%;与燃油车辆人车固定调度模式相比,人车分离能显著减少所需车辆,单线运营减少3.6%,跨线运营减少1.8%,所需司机数量基本保持不变,但司机需要换车驾驶,平均约为2次。

submitted time 2020-10-28 Hits33Downloads17 Comment 0

2. chinaXiv:201904.00072 [pdf]

Impact of Urban Rail Transit on Business Districts Based on Time Distance: Urumqi Light Rail.pdf

常烃
Subjects: Geosciences >> Geography

基于超制图学的思想,建立模型将乘坐轻轨的时间距离换算成以米(m)为单位的空间距离。在此基础上,通过地理信息系统(GIS)的地图投影空间变换方法,用换算出的距离重新定义两地间距离,变形原地图形成时间距离地图。将时间距离空间化,利用技术手段,对时间距离进行可视化表达。结果发现,轻轨对于城市形态的影响受到站点离所选取的中心点距离的影响,呈现离中心点越远变形越大;离中心点越近变形越小。轻轨对商业中心布局的影响基本呈现圈层分布。时间距离压缩了传统城市形态。随着乌鲁木齐地铁建设进程的推进和基础设施的完善,城市内部进一步压缩时间距离仍有很大余地,已有商业中心应进行升级。本研究为乌鲁木齐城市建设提供一种新的参考与思路。

submitted time 2019-03-31 Hits8906Downloads1170 Comment 0

3. chinaXiv:201804.00310 [pdf]

Analysis of the Hydroelastic Performance of Very Large Floating Structures Based on Multi-Modules Beam Theory

Xu, Jin; Sun, Yonggang; Li, Zhifu; Zhang, Xiantao; Lu, Da
Comment:本文发表在《Mathematical Problems in Engineering》
Subjects: Traffic and Transportation Engineering >> Ship Engineering

The hydroelastic behavior of very large floating structures (VLFSs) is investigated based on the proposed multi-modules beam theory (MBT). To carry out the analysis, the VLFS is first divided into multiple sub-modules that are connected through their gravity center by a spatial beam with specific stiffness. The external force exerted on the sub-modules includes the wave hydrodynamic force as well as the beam bending force due to the relative displacements of different sub-modules. The wave hydrodynamic force is computed based on three-dimensional incompressible velocity potential theory, and the boundary element method with the free surface Green function as the integral kernel is adopted to numerically find the solution. The beam bending force is expressed in the form of a stiffness matrix. The coupled motion equation is established according to the continuous conditions of the displacement and force. The motion response defined at the gravity center of the sub-modules is solved by the multi-body hydrodynamic control equations, then both the displacement and the structure bending moment of the VLFS are determined from the stiffness matrix equations. To account for the moving point mass effects, the proposed method is extended to the time domain based on impulse response function (IRF) theory. The accuracy of the proposed method is verified by comparison with existing results. Detailed results through the displacement and bending moment of the VLFS are provided to show the influence of the number of the sub-modules, and the influence of the moving point mass.

submitted time 2018-03-30 Hits2623Downloads1256 Comment 0

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