分类： 交通运输工程 >> 水路运输 提交时间： 2024-03-31
摘要： The ship motion perception approaches mainly use maritime radar, Automatic Identification System (AIS) and cameras. However, using either of these approaches alone may result in information inconsistency and insufficient data accuracy. Therefore, a multi-sensor fusion perception system is proposed in this study to monitor ship motion in inland waterways. Firstly, a hardware platform of multi-sensor fusion ship motion perception system composed of maritime radar, AIS, cameras and other accessories is constructed. Secondly, by utilizing the target detection and tracking algorithms, track association algorithms, the ship motion data collected from the three sensors are integrated. Finally, the performance of the ship motion perception system is verified by field experiments in day and night. The experimental results indicate that the integrated ship motion perception system with multiple sensors is able to improve the information consistency and data accuracy of ship motion apparently in inland waterway compared to other perception systems.
分类： 交通运输工程 >> 水路运输 提交时间： 2024-03-28
摘要： Vessel recognition plays important role in ensuring navigation safety. However, existing methods are mainly based on a single sensor, such as automatic identification system (AIS), marine radar, closed-circuit television (CCTV), etc. To this end, this paper proposes a coarse-to-fine recognition method by fusing CCTV and marine radar, called multi-scale matching vessel recognition (MSM-VR). This method first proposes a novel calibration method that does not use any additional calibration target. The calibration is transformed to solve an N point registration model. Furthermore, marine radar image is used for coarse detection. A region of interest (ROI) area is computed for coarse detection results. Lastly, we design a novel convolutional neural network (CNN) called VesNet and transform the recognition into feature extraction. The VesNet is used to extract the vessel features. As a result, the MVM-VR method has been validated by using actual datasets collected along different waterways such as Nanjing waterway and Wuhan waterway, China, covering different times and weather conditions. Experimental results show that the MSM-VR method can adapt to different times, different weather conditions, and different waterways with good detection stability. The recognition accuracy is no less than 96%. Compared to other methods, the proposed method has high accuracy and great robustness.
分类： 交通运输工程 >> 船舶、舰船工程 提交时间： 2024-03-23
摘要： 近年来，船舶智能化的发展对船舶目标的检测与分类精度要求越来越高，准确检测并识别船舶的类型及判断船舶的位置是船舶安全航行重要保障。由于船舶目标光学成像过程中易受到风、流、雨、雾等外部背景环境影响，导致基于深度学习的船舶目标检测算法性能降低；同时，船舶类型多样、形态各异以及几何尺寸大小不一等因素均使得船舶目标的检测和识别存在一定的困难。鉴于此，本文提出一种基于多尺度神经网络的目标检测方法用以提高光学影像中船舶目标的检测精度。该方法采用卷积神经网络（Convolutional Neural Networks）对图像予以特征提取，通过改进的基于CSPDarkNet骨干网络以及多尺度网络以实现船载光学摄像头对水上船舶目标的准确检测，提高模型对小目标和密集目标的检测精度。同时利用标签平滑化来防止模型陷入过拟合，并采用非极大值抑制降低重复检测。实验结果表明本文所提出的方法在Ship-Detection数据集上均值的平均精度(Mean Average Precision, mAP)可达84.80%，与Faster-RCNN、CO-DETR等先前目标检测的研究方法相比，检测效果更好，更具备潜在的应用优势。
分类： 交通运输工程 >> 道路工程 提交时间： 2024-02-07 合作期刊: 《应用力学学报》
摘要： 基于代表我国50th百分位男性人体特征的假人模型,构建了列车-假人一体化被动安全性仿真分析有限元模型,分析了列车追尾碰撞过程中乘员的运动姿态,探讨了乘员头/颈部的生物力学响应特征,揭示了座椅排次对乘员头/颈部损伤响应的影响机制,建立了基于生物力学参数的乘员头/颈部损伤风险预测模型。结果表明:追尾列车中乘员面部与前排座椅的碰撞接触可能会引起原发性脑干损伤,乘员颈部前/后弯曲均会导致下颈部颈椎出现较大应力,而颈部前/后弯曲分别导致上颈部和下颈部椎间盘出现较大应力; 现有标准中规定的Nij耐受限值会显著低估列车追尾碰撞中乘员颈部的损伤情况。
分类： 交通运输工程 >> 道路工程 提交时间： 2024-02-07 合作期刊: 《应用力学学报》
摘要： 针对我国某型大功率重载机车在高原多曲线线路上运行时频繁出现轮缘裂纹的问题,采用理论分析、数值模拟与现场试验相结合的方法对机车轮缘裂纹损伤进行研究。首先,基于多体动力学和安定理论,建立了该型大功率重载机车车辆动力学模型及轮缘裂纹损伤预测模型:其次,通过现场测试数据与数值仿真结果对比,验证了模型的正确性; 最后,根据该型重载机车运行线路特点,分析了曲线半径、曲线超高、曲线坡度等线路参数及轮缘润滑对重载机车轮缘裂纹损伤的影响规律。研究结果表明,连续小半径曲线是该型重载机车轮缘裂纹产生的主要原因,此外轮缘润滑对机车轮缘裂纹损伤有显著影响,可通过合理的线路参数设置及轮缘润滑来降低机车轮轨动态相互作用,进而减少重载机车轮缘裂纹的发生。
分类： 交通运输工程 >> 铁路运输 提交时间： 2024-02-07 合作期刊: 《应用力学学报》
摘要： 针对适于山地轨道交通的齿轨铁路,建立基于显式时间积分的三维齿轨轮对-轨道瞬态接触有限元模型,模型可分析齿轮齿条啮合和轮轨滚动接触间中、高频耦合动力作用。轮对和轨道真实几何,齿轮与车轮轮径差导致车轮悖论现象及结构振动等均有考虑,齿轮齿条啮合和轮轨接触采用集成库仑摩擦的面-面接触算法求解。对比零和非零轮轨摩擦系数工况,解构车轮悖论现象对动态接触的影响。以初步设计的Strub型齿轨铁路为例,分析速度为10 km/h和0、240、480坡度下动态接触现象。结果表明,受齿轮啮合影响,齿条、轮轨接触力均呈现周期性波动,但垂向接触总力和总牵引扭矩分别在重力载荷与牵引扭矩附近波动。车轮悖论使齿条垂向力和法向接触应力减小,而轮轨垂向力和法向接触应力增加,齿面切向接触应力与接触斑内滑移区面积相应增加,在坡度240下,轮轨摩擦系数由0增至0.2,齿条、轮轨最大法向接触应力由248.69、752.66 MPa增至195.17、757.44 MPa,最大切向接触应力相应由24.48、152.84 MPa变成21.31、2.14 MPa。轮轨接触斑因发生显著蠕滑呈现全滑移。相同速度及摩擦条件下,坡度增加使齿条垂向力和牵引力增加,轮轨垂向力和牵引力减小,接触应力呈同相变化。
分类： 交通运输工程 >> 交通运输系统工程 提交时间： 2020-10-28
摘要： 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。
分类： 地球科学 >> 地理学 分类： 交通运输工程 >> 道路工程 提交时间： 2019-03-31
摘要： 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。
分类： 交通运输工程 >> 船舶、舰船工程 提交时间： 2018-03-30
摘要： 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.
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