Locating dry ports on a network: a case study on Tianjin Port

A mathematical model for optimizing the location of dry ports is developed. The objective is to minimize the sum of the transportation costs and the fixed facility opening/closing costs. Unlike previous research on this subject, the possibility of closing existing dry ports is investigated. The dry port location problem is formulated as an integer programming and it is shown that the CFLP is a special case of our problem. The proposed model is then applied to the port of Tianjin in China and the sensitivity analysis is performed to demonstrate the robustness of the model. Our model suggests that while Tianjin Port should open some new dry ports, it might be better off closing those existing dry ports without enough throughputs. Although all parameters estimated should be uncertain in reality, sensitivity analysis shows that the results returned by the model are quite stable.     

使用相位共轭阵列进行声源定位的相关参数研究

基于相位共轭方法采用离散阵列对用于声源定位的相位共轭阵列参数进行了数值计算研究,研究了阵元间距、阵列面积、声源频率和阵列形式等对声场聚焦幅值和空间尺寸大小的影响.数值计算结果表明:采用平面阵列,为突破声波衍射极限,阵元间距应为△≤0.5λ,最优的阵元间距为0.15λ.在近场基于声压梯度测量使用偶极子源的相位共轭阵列,阵列边长满足a≥1.4λ即可,并且随着频率升高,相位共轭声场的幅值增大,得到的相位共轭分辨率降低.对于阵列形式,采用十字交叉阵列可用较少的阵元个数就可以突破衍射极限.如果阵列与声源为共形面,推导出相位共轭声场幅值与声源的辐射声功率成比例,文中还计算并验证了相位共轭声场幅值与辐射立体角的关系.     

基于运输规模效应的城市客运枢纽选址模型研究

基于枢纽建设的运输规模效应,考虑路网运输费用平衡流量分配关系和可能产生的路段扩容需求,构建以枢纽建设费用和网络运输费用以及路段扩容费用组合最优为目标函数的数学模型,并结合Dijkstra算法和枚举法进行算例计算与分析。结果表明,该模型可以从比较综合的角度为城市客运枢纽选址提供理论支撑。     

珠三角城际轨道交通枢纽站点布局研究

珠三角城际轨道交通线网要求＂统一规划、统一建设、统一标准、统一运营＂,线网内部要求实现互连互通、运营灵活、资源共享,需要进一步深入研究＂互连互通＂的内涵。阐述了城际轨道交通综合交通枢纽的设计新理念,提出了基于珠三角城际轨道交通线网的枢纽站点分类和衔接原则,通过研究主要枢纽站点衔接方式,初步形成了珠三角城际轨道交通枢纽的基本框架。     

基于EKF的双站测向无源定位跟踪方法研究

对双站测向无源定位跟踪方法进行了研究,分析了双站交叉定位的基本原理,采用扩展卡尔曼滤波对三维空间中的机动目标无源定位跟踪问题进行了仿真分析。仿真结果表明,在假设的仿真条件下以及测向精度为0.001rad时,对机动目标定位跟踪的相对测距误差保持在2%以下,滤波跟踪效果良好,表明该方法对无源定位跟踪是有效的,对工程应用有一定指导意义。     

水火弯板残余变形预报的数值和量纲分析(英文)

Line heating process is a very complex phenomenon as a variety of factors affects the amount of residual deformations. Numerical thermal and mechanical analysis of line heating for prediction of residual deformation is time consuming. In the present work dimensional analysis has been presented to obtain a new relationship between input parameters and resulting residual deformations during line heating process. The temperature distribution and residual deformations for 6 mm, 8 mm, 10 mm and 12 mm thick steel plates were numerically estimated and compared with experimental and published results. Extensive data generated through a validated FE model were used to find co-relationship between the input parameters and the resulting residual deformation by multiple regression analysis. The results obtained from the deformation equations developed in this work compared well with those of the FE analysis with a drop in the computation time in the order of 100 (computational time required for FE analysis is around 7 200 second to 9 000 seconds and where the time required for getting the residual deformation by developed equations is only 60 to 90 seconds).     

铁路客运专线与城市交通的衔接及站点选址评价方法研究

分析了铁路客运专线与城市交通的衔接体系的组成要素,提出了铁路客运专线与城市交通衔接的具体目标,运用层次分析法建立了铁路客运专线车站选址的评价指标体系和评价模型.     

柴油机轴系扭振振幅异常分析与故障处理

通过对R16V280ZJ柴油机试验台轴系的扭振计算和实测对比,分析试验台位轴系扭振产生振幅异常的原因,从而有效实现故障排除。     

细长轴的火焰矫直法

文章就船舶轴系中细长轴弯曲变形矫直工艺的火色与温度、最大弯曲值的确定、加热变形量的测量与监控、加热点位置与数量的确定、火焰调节、临界温度火色的观察与环境因素的影响作了探讨。     

行波法在铁路自闭／贯通线故障测距中的应用

铁路自闭/贯通线路故障点的精确查找对于提高系统供电可靠性具有重要意义。本文介绍了行波故障测距的基本方法和现阶段已解决行波测距的关键技术;结合自闭/贯通线路自身的特点,对行波法在故障测距应用中存在的问题及解决方案进行了归纳总结。最后展望了行波测距在自闭/贯通线路中广泛应用需进一步研究的问题和难点。