Transport properties in a multi-terminal regular polygonal quantum ring with Rashba spin-orbit coupling

Transport properties in a multi-terminal regular polygonal quantum ring with Rashba spin-orbit coupling （SOC） are investigated analytically using quantum networks and the transport matrix metLod. The results show that conduc- tances remain at exactly the same values when the output leads are located at axisymmetric positions. However, for the nonaxisymmetrical case, there is a phase difference between the upper and lower arm, which leads to zero conductances appearing periodically. An isotropy of the conductance is destroyed by the Rashba SOC effect in the axisymmetric case. In addition, the position of zero conductance is regulated with the strength of the Rashba SOC.

Terminal Location Models for Intermodal Transport Network Optimization

Since rail-road transport uses road and rail networks and requires the transshipment infrastructures at the terminals, its competitiveness depends not only on the costs but also on the location of these terminals. This paper focused on providing a methodology for determining the optimal locations for intermodal freight transportation terminals in consolidation network. The goal is to minimize total costs in order to increase the efficiency of the transportation system. This paper also has allowed us to have an overview of the methods and models that exist for solving the problem of intermodal and terminal locating.

Polarization resolved analysis of phonon transport in a multi-terminal system

The atomistic Green’s function method is improved to compute the polarization resolved phonon transport in a multiterminal system. Based on the recent developments in literature, the algorithm is simplified. The complex phonon band structure of a semi-infinite periodic terminal is obtained by the generalized eigenvalue equation. Then both the surface Green’s function and phonon group velocity in the terminal are determined from the wave modes propagating away from the scattering region along the terminal. With these key ingredients, the individual phonon mode transmittance between the terminals can be calculated. The feasibility and validity of the method are demonstrated by the chain example compared with the wave packet method, and an example of graphene nanojunction with three terminals.

Modelling Dry Port Systems in the Framework of Inland Waterway Container Terminals

Overcoming the global sustainability challenges of logistics requires applying solutions that minimize the negative effects of logistics activities.The most efficient way of doing so is through intermodal transportation(IT).Current IT systems rely mostly on road,rail,and sea transport,not inland waterway transport.Developing dry port(DP)terminals has been proven as a sustainable means of promoting and utilizing IT in the hinterland of seaport container terminals.Conventional DP systems consolidate container flows from/to seaports and integrate road and rail transportation modes in the hinterland which improves the sustainability of the whole logistics system.In this article,to extend literature on the sustainable development of different categories of IT terminals,especially DPs,and their varying roles,we examine the possibility of developing DP terminals within the framework of inland waterway container terminals(IWCTs).Establishing combined road–rail–inland waterway transport for observed container flows is expected to make the IT systems sustainable.As such,this article is the first to address the modelling of such DP systems.After mathematically formulating the problem of modelling DP systems,which entailed determining the number and location of DP terminals for IWCTs,their capacity,and their allocation of container flows,we solved the problem with a hybrid metaheuristic model based on the Bee Colony Optimisation(BCO)algorithmand themeasurement of alternatives and ranking according to compromise solution(i.e.,MARCOS)multi-criteria decision-making method.The results from our case study of the Danube region suggest that planning and developingDP terminals in the framework of IWCTs can indeed be sustainable,as well as contribute to the development of logistics networks,the regionalisation of river ports,and the geographic expansion of their hinterlands.Thus,the main contributions of this article are in proposing a novel DP concept variant,mathematically formulating the problems of its modelling,and developing an encompassing hybrid metaheuristic approach for treating the complex nature of the problem adequately.

Intermodal Terminal Localisation Using a Linear Programming Approach: The Case Study of Togo and West African Landlocked Countries

In this paper, four potential cities to host an intermodal terminal for containers flowing through the Togolese transport corridor are examined. The transport cost minimization through the corridor is the main objective. Consequently, the transport modes that offer the least cost to the transport supply chain are proposed. To attain this goal the paper aims to identify the optimal location for an intermodal terminal on the Togolese corridor, by using the mathematical linear programming model. For this, three transport scenarios are analyzed, the rail, the road, and the combination of these two transport modes to each of the landlocked countries (LLCs) capital cities of Burkina Faso, Mali and Niger. Data of the average transport cost per mode, the cargo demand of the LLCs, and the distances from origin to destinations are input in the LINGO software. Based on the optimization results, we find that among the preselected terminals, the city of Mango located at 550 km in the northern part of the country is the optimal host location for an intermodal terminal along the Togolese corridor. The results of this study may be helpful to transport policy makers in the quest of rendering better servicing to the landlocked countries.

Electronic Transport Properties of Transition-Metal Terminated Trigonal Graphene Nanoribbons

With the non-equilibrium Green’s function method and density functional theory, we have studied the electronic properties of trigonal graphene nanoribbons, with Fe terminal and H terminal, coupled to gold electrodes. Rectification behavior can be observed when the electrode-molecule contact distance is larger than 2.2 &Aring. The electronic transport is greatly improved in case of Fe terminal which is analyzed in terms of transmission spectra and density of states.

城市过饱和区域积分终端滑模控制算法

【目标】现有基于滑模变结构的区域边界控制算法存在明显缺陷,即系统状态需要在时间趋于无穷大时才能收敛到平衡点,仅能保证系统的渐进稳定。这显然无法满足现代城市交通管理对于快速响应和高效调控的需求。为克服该局限,提出一种基于宏观基本图和积分终端滑模的区域边界控制算法,获得较快的收敛速度以及较好的鲁棒性和扰动抑制特性。【方法】首先,将干扰(非门控或区域内部交通量)和宏观基本图建模中的不确定性视为集总干扰,建立城市过饱和区域边界控制系统模型。在此基础上,引入非线性积分终端滑动超平面,设计一种基于积分终端滑模的边界控制算法。【结果】将所提方法应用于5×5均匀棋盘路网中,路网累积空间交通流量有超过1%的提升,部分算例中接近5%;平均速度有超过5%的提升,部分算例中超过8%。所提出算法具有较快的收敛速度和较好的扰动抑制能力,能显著提升路网累计吞吐量和路网中车辆平均速度,缓解过饱和区域交通拥堵。【结论】相较于既有滑模变结构边界控制算法,所提出算法采用非线性积分终端滑动超平面,能保证受控路网状态在预设有限时间内收敛到期望状态;相较于既有比例积分控制策略,能更好处理受控路网中非常值干扰交通需求和宏观基本图建模中存在的低离散度。

基于智能终端定位的智能交通系统设计与实现

该文主要研究基于智能终端定位的智能交通系统的设计要点与实现方式。该系统采用C/S架构,服务器端可根据用户的位置、速度信息,以及交通事故和道路施工位置信息,实现对车载终端的实时和精准定位,并向车载终端发送交通流量信息。该系统从百度、高德、Google地图获取图片并构建地图引擎,将交通流量计算结果和预测结果以Socket通信或短消息通信等方式发送给用户,以便于用户合理规划行车路线,对缓解交通拥堵、提高出行效率有积极帮助。

Some possible station layouts and characteristics of evacuated tube transportation

Since Maglev vehicles will run in a closed vacuum tube,the layout of the terminal stations of evacuated tube transportation（ETT） will differ from the traditional railway stations.This paper deals with some possible station layouts of ETT,e.g.,a station with an airlock,a station without an airlock,above ground and underground stations,and stations with either level arrayed or rotation platforms.Then different station layouts are compared,and characteristics of each are analyzed.Finally,a more secure mode for ETT station layouts is suggested,which can be the basis for future ETT station layout and designs.

基于注意力Seq2Seq模型的终端区航空器航迹预测

为充分挖掘机场终端区航空器航迹时间依赖性,解决中长期、多步长航迹预测精度不稳定的问题,引入注意力机制(attention mechanism)和教师监督(teacher forcing)中的指数衰减(exponential decay)采样方法,提出了一种基于序列到序列框架的机场终端区航迹预测模型(Seq2Seq-attention mechanism-exponential decay,SAE)。序列到序列框架实现了多步长预测,注意力机制提高解码器预测精度,指数衰减采样方法加速了训练阶段模型收敛,在一定程度上提高了模型的泛化性。最后,为了验证提出方法的有效性,利用天津终端区28架次、90 d ADS-B航迹数据构建原始数据集,以平均绝对误差(mean squared error,MAE)和均方根误差(root mean squared error,RMSE)作为模型性能评价指标,进行了航迹预测实验,实验结果表明:高度、经度和纬度在序列到序列框架中的循环神经网络分别采用LSTM、GRU和LSTM可以获得最好预测性能;以4种预测长度1、3、5和10 min进行建模,与基线模型中预测性能最好的结果比较,所提出方法在验证集上的高度、经度和纬度指标表现最优,10 min预测窗口下的平均绝对误差分别降低了66.30%、54.62%和36.59%,均方根误差分别降低了65.45%、38.16%和20.57%,同时,上述4种预测时长下所提出方法预测结果的均值和方差最小,表明随着预测时长的增加,模型预测结果的稳定性最好。此外,引入的注意力机制与指数衰减采样方法对有效捕捉航迹时间依赖性、提高模型泛化性均具有积极的贡献。

终端空域航段拥堵演化机理尖点突变分析模型

为保障终端空域正常运行,对终端空域拥堵演变机理进行研究。将拥堵分为自身结构致因和外部因素致因两类,建立了拥堵形成与消散的分析模型;依据交通流演化的特征指标及Greenshields理论建立了拥堵机理尖点突变分析模型。以成都终端空域为研究对象,利用AirTOp软件生成仿真运行数据,验证了模型有效性。结果表明,所设计模型可有效描述拥堵演化的宏观过程,通过航段当量流量、密度及波速的变化,可有效对拥堵演化的机理进行分析。

考虑延误特征的航站楼离港聚集客流预测方法

为满足航班延误下航站楼内资源规划与旅客管理对聚集客流预测所提出的高精度和高效率要求,本文提出一种融合延误特征的离港聚集客流预测方法。通过引入航班延误特征量化表征航站楼离港聚集客流的波动情况,探究航班延误下离港聚集客流波动规律和分布特征,构建基于自适应噪声完全集合经验模态分解(CEEMDAN)、排列熵算法(PE)以及鲸鱼优化算法(WOA)优化的长短期记忆神经网络(LSTM)的短期航站楼聚集客流预测模型。首先,应用CEEMDAN将聚集客流数据序列分解为若干模态分量(Intrinsic Mode Function, IMF)和残差量(Residual, Res),降低原序列中数据的复杂性和非平稳性影响;其次,为减小模型计算规模,同时提高预测效率和精度,采用PE算法对IMF分量进行熵值重构;最后,建立WOA-LSTM聚集客流预测模型,利用鲸鱼优化算法优化LSTM超参数,叠加重构分量的预测结果,得到最终的聚集客流预测值。将模型应用于长三角某枢纽机场进行实例验证。结果表明:CEEMDAN-PE-WOA-LSTM预测模型性能最优,相较单一的LSTM模型,候机大厅聚集客流预测的均方根误差、平均绝对误差以及百分比误差分别降低42.78%、44.00%及45.62%;相较CEEMDAN-WOA-LSTM模型,预测效率提高41.64%。本文所提模型能够有效拟合存在显著非线性和非平稳性特征的候机大厅聚集客流,具有较高的预测精度和运算效率。

当前大城市交通问题的思考与路径选择--中国城市交通发展论坛第37次研讨会

中国城市交通基础设施建设由增量向存量发展,新兴交通方式迅速崛起,个性化出行需求与集约化供给要求间的结构性矛盾日益凸显。探索解决当前大城市交通面临突出问题的有效路径,是城市可持续发展之所需。中国城市交通发展论坛于2024年7月5日在广州市举办了2024年第3次(总第37次)常规研讨会,主题为“当前大城市交通问题的思考与路径选择”。与会嘉宾聚焦转型期城市交通规划面临的机遇与挑战、新技术新思维对行业的冲击、绿色交通方式的发展困局与突破路径等方面展开研讨,提出多项城市交通转型升级发展策略。本次论坛由中国城市交通发展论坛组委会主办,广州市交通规划研究院有限公司承办。

集装箱海铁联运运输组织优化研究综述

多式联运是集装箱运输组织的高级形态,而海铁联运作为两种运输批量最大的运输方式的组合,具有其他联运方式所无法比拟的规模与成本优势。近年来,随着中欧集装箱班列规模的不断扩大,我国海铁联运虽然得到了迅猛发展,但是与发达经济体20%~40%海铁联运占比相比较,我国占比不到3%还有巨大的增长空间。鉴于此,基于海铁联运运输组织优化的“软衔接”视角,从港站堆场资源配置协同、换装作业协同、班列开行方案优化三个维度对集装箱海铁联运相关研究进行梳理和评述,并提出潜在研究方向,以期对集装箱海铁联运的运输组织优化提供决策参考。

新型双层集装箱列车铁水联运同步装卸技术

双层集装箱铁水联运具有运量大、单位运输成本低、运输持续稳定等优势,因此近3年来我国在宁波舟山港积极推进双层集装箱铁水联运的创新试点。然而,普通双层集装箱列车在传统码头的装卸作业受配载计划、装卸设备、车辆调度等限制,不利于实现港口集装箱快速集散。本研究提出一项新型双层集装箱列车同步装卸方案,以提升铁水联运码头作业效率。具体而言,在硬件装备上,创新设计出一款兼具装卸功能的自动导引运输车(AGVH)和新型双层集装箱运输专用平车;在堆场布局上,提出在集装箱码头和货运站新建或改造双层箱堆场(含立体堆场);在作业流程上,设计了集装箱从班轮运至内陆货运站的系统过程,并对列车在码头分别应用新型双层箱同步装卸方案和传统装卸工艺的效果进行对比测算和灵敏性分析;在方案评估上,研究了在现行配载规则、运输限界和重心高度要求下,各双层箱堆叠形式的可行性。研究证明了新型双层集装箱列车同步装卸技术在减少集装箱装卸时间和作业成本方面具有显著优势,同时丰富了双层箱的装载形式以降低配载计划复杂度和不同类型箱源组织难度,有助于推动港口集疏运系统降本增效。

基于UWB的矿用一体化智能车载终端的设计

设计了1种基于UWB精确定位技术,融合精确定位、4G/5G无线通信、视频监控、数据采集、语音通话等多种功能于一体的智能车载终端。智能车载终端采用安卓平台,以ARM RK3399为控制核心,以UWB通信收发芯片DW1000为精确定位核心,实现了井下车辆的精确定位、智能调度、信息采集、安全预警、语音通话、人机交互等功能。测试结果表明:车载终端最大动态定位误差不大于7.3 m,满足煤矿对智能辅助运输的各项功能需求.

终端区交通态势利导及实现方法

终端区交通态势感知技术相关研究已有成果,如何借助终端区态势感知技术优化终端区交通态势,当前还未有明确的方法。由此提出终端区态势利导的概念,将实现态势利导的关键技术分为3类,并分别做了详细阐述。在传统的时隙分配模型上,加入航空公司偏好性,建立两阶段时隙调配机制:第1阶段,构建了一个对各航空公司公平的参考时刻表;第2阶段,通过调整参考时刻表以尽可能多地满足这些航空公司关于时刻表中位移分配的请求。算例结果表明:根据所提时隙调配机制得到的时刻表不仅满足了公平性,还提高了航空公司对其的接受性,并分析了该机制对繁忙终端区交通态势的良性引导作用。

基于运载能力的铁路集装箱中心站轨道吊与集卡协同优化

为解决铁路集装箱中心站设备资源有限的问题,本文基于集卡实际运载能力,研究铁路集装箱中心站集卡“一车两箱”模式下,“轨道吊-集卡”协同优化问题,并构建以集卡作业完成时间最短为目标的整数规划模型,同时,考虑集卡运输不同尺寸集装箱的决策以及轨道吊的安全约束等实际情况。为求解模型,设计考虑轨道吊分配策略的遗传模拟退火算法,并进行3组不同规模的实验,验证模型和算法的可行性和有效性。实验结果表明,与传统集卡“一车一箱”模式下,“轨道吊-集卡”协同作业相比,集卡“一车两箱”模式下,作业完成时间平均缩短了13.3%,并且随着算例规模的增大,集卡“一车两箱”模式的作业完成时间缩短越明显;同时,集卡“一车两箱”模式下,轨道吊作业更加灵活且作业量更均衡;此外,当铁路集装箱中心站集卡资源有限时,集卡“一车两箱”模式也可以提高设备的利用率。

自动化集装箱堆场的通信信号关键技术研究

针对铁路作业线引入自动化集装箱码头铁路堆场交接作业难题,为保证铁路方和码头方的作业安全并提高铁路及码头的作业效率,梳理出一整套作业流程、安全措施,系统研究交接过程中的作业人员安全保障技术、作业机械安全互锁与动态防护技术、信息系统的沟通和整合技术、车辆状态检测及自动化机械装置等关键技术,提出整套解决方案,解决多式联运港口自动化交接作业难题,消除铁路交叉区的安全作业问题,从而提高港口整体运输效率,提升码头堆场的智能化水平。

多振源激励下武汉站振动实测与舒适度研究

为了研究综合交通枢纽中地铁、高铁和行人等振源单独作用和共同作用下楼板的振动响应问题,以武汉站为例,对其站厅层开展现场振动实验测试,并结合标准JGJ/T 170—2009对站厅层进行了振动舒适度评价。时域分析结果表明:列车产生的振动传递到站厅层,会在各个结构柱处产生一定的放大;振源数目对水平方向加速度的影响大于对竖向加速度的影响;站厅层一跨内的振动传递特性可近似用二次函数递减推算。频域分析结果表明:站厅层的振动频率均集中在0~100 Hz;随着测点距离的变化,高频成分发生明显衰减,但10~20 Hz处的低频成分并没有随着距离的增加而出现明显的衰减。振动舒适度评价表明:武汉站站厅层的振动舒适度符合规范要求,但长期处在振动的环境中,会对工作人员的身心产生一些影响。该研究对新建综合交通枢纽的设计和在役交通枢纽的正常运行维护具有一定的指导意义。