The optimization problem of multi-stage disaster response capacity of road transportation network was analyzed in order to reduce the cost of disaster response for road network and ensure the rapid connectivity of road network. A three-layer planning model for the selection of comprehensive pre-disaster emergency workstations and post-disaster road network recovery decisions was established. The differences in exhaustibility, transportation mode and recovery effect of emergency rescue equipments and logistics support resources were specially considered, and the interdependent relationship between the two was quantitatively modeled. An approximate optimal solution for the model was obtained by combining the bi-level genetic algorithm and the Frank-Wolfe algorithm. The research results show that the optimal decisions can respectively reduce the transportation cost of logistics support resources by 10.96% and the weighted recovery cost by 11.51% compared with the pre-disaster deployment decisions not considering the post-disaster recovery process and the decisions not considering the pre-disaster layout decision of logistics support resources. The quantity of logistics support resources and emergency rescue equipments layout jointly affect the recovery effect of the road network. The impact of increasing the quantity of emergency rescue equipments on the recovery effect will be overestimated if the interdependent relationship between the two is neglected.

To explore and alleviate large-scale failures under urban rail transit network accidents, cascading failures are usually investigated integrating the network topology and passenger flow. However, the impacts of the het-erogeneity of travel demand and its interactions with the spatiotemporal heterogeneity of rail passenger flow on cascading failures are still left unknown. In this study, the dynamic changes of origin-destination travel demand under failures, the time-delay of cascading failures and the interaction between these dynamic properties and spatiotemporal heterogeneity of passenger flow are modeled and explored in an improved disaster spread theory model. The approach is applied to Shanghai urban rail transit network under different attack scenarios. Results show that the scale of cascading failures on Shanghai urban rail transit network importantly depends on the ratio of passengers changing travel demand and time-delay of cascading failures. Besides, large in-flow of stations adjacent to the failed station would not only cause fast spread of cascading failures at the early stage but also result in many failed stations in the end. The heterogeneity of passenger flows in different directions on the network would reduce the scales of cascading failures. It is also found out that the circle line could obviously prevent the spread of cascading failures.

为探究城市居民低碳出行意向与行为差异的原因和异质性,基于大中小城市、老中青群体1263名居民的低碳出行问卷调查数据,采用双变量Probit模型和组间平均边际效应(AME),分析了城市和群体间低碳出行意向与行为一致性的影响因素及群体差异.结果表明:有低碳出行意向与行为的居民比例仅为12.6％,有低碳出行意向而未向行为转变的居民占55.3％,意向与行为不一致的现象在一线城市和青年群体中尤为明显.从平均边际效应的结果看,有无私家车是导致一线、二线城市居民和中、青年群体低碳出行意向与行为不一致的关键因素.环境意识和主观规范对老年群体的低碳出行意向与行为一致性具有更显著的积极影响.研究所揭示的影响不同群体低碳出行意向与行为一致性的关键因素,可为低碳政策的异质化实施提供理论参考.

为探究智能网联车辆(CAV)与人工驾驶车辆混行情况下快速路的宏观交通流特性,研究了CAV渗透率对快速路宏观基本图(MFD)的影响规律.首先,利用MFD临界点和拥堵拐点的特征属性,构建考虑CAV渗透率的MFD分段拟合模型;其次,从拥堵持续时间、拥堵严重程度和MFD迟滞现象3个方面分析CAV渗透率对快速路拥堵过程的影响;最后,采用SUMO搭建仿真环境,对提出方法进行验证.结果表明:提出的分段拟合方法在拟合优度及跟踪MFD临界点上均优于三次拟合方法;CAV的引入并不会消除快速路MFD的迟滞现象,但其持续时间会随着CAV渗透率的增加而降低;快速路拥堵严重程度随CAV渗透的增大而降低,当CAV渗透率超过0.5时,拥堵的改善效果开始减弱.

地铁网络突发重大事故后,通常会启动公交接驳疏散滞留乘客.提出衡量网络性能的网络效率可达性指标,考虑地铁站点发生故障后公交接驳对乘客的紧急疏散作用.基于网络效率可达性指标构建韧性评估模型,提出多故障下以韧性最大化为目标的修复策略,并以上海市地铁网络为例进行实例研究.研究结果表明,单个站点发生故障后启动公交接驳可使网络性能损失降低5.1％;占网络站点总数2.14％的多个站点发生故障后启动公交接驳可使网络性能损失降低13.48％;多故障下相比基于站点度、介数、脆弱性等评估得到的修复序列,基于韧性评估得到的最优修复序列可使网络性能累积损失降低2.86％.此外,研究发现在公交接驳场景下,当地铁网络中多个站点发生故障后,优先修复客流量大、站点周边线路稀疏、失效后造成影响大且修复时间短的站点,有助于降低网络性能的累积损失.

In order to explore the vulnerability of the rail transit network after multiple associated stations were deliberately attacked and the differences in the impact of different attacks, the correlation between multiple stationswas measured and analyzed, and the vulnerability quantification method of the rail transit network under the coordinated attack of the associated stations was given. An attack model aiming at maximizing vulnerability was proposed, and the model was solved by immune algorithm to obtain the optimal attack strategy. Taking Shanghai metro network as an example, the vulnerability of rail transit networks under multi stations coordinated attack was studied. The results show that the vulnerability of rail transit networks under multi stations deliberate attack depends not only on the importance of each station, but also on the correlation between different stations, especially the spatial location correlation and passenger travel correlation. Multiple transfer stations located on different lines and with large passenger flow have the highest vulnerability to coordinated attacks. After multiple stations accounting for 3.56% of the total number of network stations are attacked at the same time, the rail transit network performance loss can reach up to 63.61%.

Because natural disasters, operational incidents, and terrorist attacks are posing increasing threats on railway systems, their vulnerability and resilience have become important concerns for researchers and practitioners worldwide. This chapter discusses the vulnerability and resilience of railway systems under disruptions from conceptual, methodological, and practical perspectives. The chapter begins with a comprehensive review of the literature as well as findings of current research. Methodologies of railway system vulnerability and resilience based on the accessibility theory are then presented and discussed, respectively. Railway system practices of two Chinese cities, Shanghai and Shenzhen, are then demonstrated with the proposed methodologies. Based on the analyses results, vulnerability and resilience evaluations are helpful in identifying the most vulnerable stations and enhancing railway system robustness and resilience. Significant practical implications are identified for railway planners and managers under disruptions. Finally, conclusions are drawn for railway system vulnerability and resilience.

为总结城市轨道交通网络关键站点识别方法的研究成果,推动其在关键交通设施保护领域的更广泛应用,调研了关键站点识别方法的研究现状,总结了国内外城市轨道交通网络关键站点识别的主要方法,并以上海市地铁网络为例对不同方法进行了对比与分析.结果表明:不同方法识别出的关键站点的分布规律存在差异,基于站点度中心性和介数中心性识别出的关键站点主要是网络中的换乘站点;基于站点紧密中心性识别出的关键站点主要分布在网络中心区域;但是基于网络效率损失识别出的关键站点主要位于环形线路和临近环形线路向外辐射的支路上.研究还发现:不同方法之间的相关性大小存在差异,对于客流介数中心性高的站点,一旦失效后对网络可达性损失的影响也较大;对于失效后造成乘客未满足出行需求高的站点,一旦失效后对网络效率损失的影响也较大;但紧密中心性较高的站点失效后对网络可达性损失和网络效率损失的影响并不显著.

针对高铁站周边路网交通流量大、客流集散需求高、道路网络单元耦合作用显著的特性,在网络拓扑结构的基础上,提出考虑交通需求动态变化和网络单元耦合作用的高铁站周边路网风险辨识模型.以西安北站周边路网为例,研究了不同交通需求下高铁站周边路网风险节点的动态变化,分析了周边网络中高风险节点失效造成的影响;并与未考虑网络单元耦合作用的风险辨识模型进行了比较,验证了所提出模型的优越性.研究结果表明,不同交通需求下,高铁站周边路网风险节点的空间分布具有差异性,距高铁站1km范围内耦合作用强的路段和交叉口风险变化更显著;当交通需求增大到原来的3倍后,节点和路段的风险显著增加,风险变化率最高达到20％;当交通需求增大到原来的5倍后,节点和路段风险变化率最高达到42％;网络单元失效后用户平均出行时间损失最高可达2.7h.考虑网络单元耦合作用的风险辨识模型可有效识别动态交通需求下网络风险的动态变化,从而保障路网的可靠运行.

In terms of urban rail transit network vulnerability, most studies have focused on the changes of network topology and functional characteristics under disruptive events while ignoring the impacts of cascading failures on network performance. In this study, an improved Coupled Map Lattices model is proposed to address the evolution process of cascading failures on rail transit network. Particularly, the model quantifies important factors of cascading failures integrating quantitative failure spreading mode, anti-risk ability of stations, and perturbation index. The rail transit network vulnerability is then modeled addressing numbers of failed stations, degree of affected passengers, and loss of passenger travel time as a result of cascading failures. The methodology is applied to the metro network of Shanghai, China. Results show that the propagation of network cascading failure depends on the station's anti-risk ability, geographical location, and type of adjacent stations. Stations located in the urban center area are more susceptible to failures of adjacent stations. Furthermore, higher affected passenger volume and station coupling strength would lead to more serious and rapid spreading of failures, and thus more vulnerable of the metro system. However, the anti-risk ability of stations could effectively resist the spread of failures in the early stage, and stations with higher topology redundancy demonstrate stronger anti-risk ability.

Various disruptions such as natural disasters, malevolent attacks, and emergencies are still inevitably posing threats on road networks in the driverless environment. However, most studies have focused on the impacts of micro mixed traffic flow characteristics, which cannot explicitly measure road network vulnerability in driverless environment. This paper develops a bi-objective framework to construct driverless environment based on travel demand. An improved accessibility-based methodology integrating traffic flow and driverless conditions evaluates the vulnerability of road network under disruptions. The proposed methodology was applied to the highway network in Florida, USA. Results demonstrate that the vulnerability of road network would be decreased with the increase of the penetration rate of autonomous vehicles. When the penetration rate gets in the range of 40%-80%, network vulnerability would significantly reduce, and they show linear relationship. Findings of this study could provide new sights into managing and planning driverless road network in future.

为明确城市轨道交通网络不同站点的重要程度,提出基于网络冗余性识别关键站点的方法,从网络拓扑结构和交通功能特性2个角度定义拓扑冗余性和功能冗余性,并以上海市地铁网络为例,识别关键站点.研究结果表明:基于拓扑冗余性识别出的单个重要站点失效后,将导致网络中13.15％的交通出行(起点-终点,OD)无法连通;基于功能冗余性识别出的单个关键站点失效后,将导致网络中10.1％的乘客无法通过轨道交通网络完成出行.对于环形辐射状的轨道交通网络,基于网络冗余性识别出的关键站点主要分布在环形线路和临近环形线路向外辐射的支路上.此外,多个站点同时失效后,对网络造成的影响不仅取决于每个站点的重要程度,还取决于每个站点在轨道交通网络中的空间位置分布.

城市轨道交通网络少数关键站点发生故障可能导致整个网络性能下降甚至瘫痪.现有基于节点重要性贡献矩阵识别网络关键节点的方法忽略了网络功能特性的解析,无法准确识别运营过程中城市轨道交通网络关键站点.通过改进传统节点重要性贡献矩阵,在节点效率的评估中考虑客流运输,在节点重要度贡献矩阵中考虑多阶邻接节点的贡献及网络交通特性,提出站点重要性的量化指标.利用该方法识别上海市地铁网络关键站点,通过模拟对关键站点的攻击以及与传统识别方法的比较,对所提出的关键站点改进识别方法进行验证.研究结果表明:相比于传统节点重要性贡献矩阵,基于改进节点重要性贡献矩阵识别出的关键站点失效后,对城市轨道交通网络效率及网络效率可达性的影响更大;单个站点失效后对网络效率造成的损失最高可达8％,对网络效率可达性造成的损失最高可达10％.同时还发现,基于改进方法识别出的关键站点不一定是分布在网络中心区域的换乘站,客流量大且周边线路稀疏的非换乘站点也同样重要;当占网络站点总数5％的关键站点失效后,对网络效率造成的损失可达70％,对网络效率可达性造成的损失可达67％,因此关键站点的识别与保护将有助于最大程度地降低系统损失和保障交通系统安全稳定运行.

Evidences demonstrate that real-world networks are becoming more and more interacted with each other. Most studies have contributed to the analysis of interdependent networks in topology. However, existing researches usually address the impacts of topology connectivity, and ignore the function interdependency between networks underestimating the performance of interdependent networks under failures. Therefore, the function interdependency is left unknown and unexplored. This study presented a supply-demand-based interdependency approach integrating topology and function interdependency. The proposed approach not only captures the function interdependency, but also explores bidirectional dependency between interdependent networks. The methodology was applied to the interdependent metro and bus networks of Xi'an, China. Results demonstrate that topology and function characteristics have joint effects on network interdependency. The similarity in network topological connectivity and function would increase network interdependency. Furthermore, function dependency has a dominant impact on interdependent networks. Even if the topology dependency is significantly decreased under failures, the performance of interdependent networks would depend largely on the bidirectional function dependency. Improving the network interdependency could increase the capacity of both networks against attacks. Findings of this work would have implications for the planning and emergency responses of interdependent infrastructure systems building resilient network of networks under disruptive events.

为准确地评估突发事件下轨道交通网络的脆弱性,提高网络抵抗风险的能力,在轨道交通拓扑脆弱性研究的基础上,考虑网络中实际的客流以及站点失效情景下公交对客流的接驳作用,基于用户的平均出行时间损失构建脆弱性评估模型,以上海市地铁网络为例,识别出网络中的关键站点,同时,分析不同公交接驳效率对轨道交通网络脆弱性的影响.研究结果表明:在公交接驳场景下,轨道交通网络中时间加权度和客流介数中心性较高的站点一旦失效,对用户造成的平均出行时间损失较大;此外,公交接驳效率越高,轨道交通网络的脆弱性越低,当公交接驳效率高于0.4时,对用户造成的平均出行时间损失可降低到5％以下.

Although the wireless power transfer (WPT) system for electric vehicles (EVs) provides numerous advantages, there is still a low coupling coefficient and the misalignment between the primary coil and the secondary coil needs to be solved. In this paper, the transmission efficiency and transmitted power were calculated based on Series-Series (SS) compensation topology. The coupling coefficient is related to the coil parameters and misalignments. A simulation study was carried out to explore the variation in the coupling coefficient for different coil configurations under different air gaps and coil misalignments. Moreover, the influence of the internal parameters of the square coil on the coupling coefficient was further studied. Finally, this paper discusses the influence of ferrite cores with a square coil on the coupling coefficient. The results of this paper show that designing the optimal internal parameters of the square coil and the ferrite core can increase the coupling coefficient between the coils, which can also provide guidelines for the design and optimization of the magnetic coupling coils for a wireless charging system for electric vehicles.

To study the inherent characteristic of occurrence of vertical vortex-induced vibration on the bluff box girder and the law of the aerodynamic measure taken for suppressing the vibration,the vibration displacement and surface pressure of the model of the box girder were synchronously measured through the wind tunnel test.Based on the pressure time-history of the different measurement points on the model,the mean values and mean square deviations of the pressure coefficients,the correlation and degree of the contribution of the local aerodynamic forces to the total aerodynamic force were comprehensively compared and analyzed.The results of the analysis reveal that the fundamental cause leading to the occurrence of the vertical vortex-induced vibration on the section of the bluff box girder is that the upstream separated airflow causes the remarkable increase of the middle stream and downstream pulse pressure.The middle stream and downstream lift forces have good correlation to the total lift force and have the greatest contribution to the vortex-induced vibration.The arrangement of the closed balustrades on the box girder can suppress the vertical vortex-induced vibration on the section of the girder.The changing of the wind resistant ratios of the balustrades will simultaneously change the intensity of the pressure pulse distribution on the upper and lower surfaces of the girder,however,the changing can only change the mean values of the pressures coefficients of the upper surface.The mechanism of the aerodynamic measure for suppressing the vibration is to weaken the intensity of the middle stream and downstream pulse pressure and to destroy the correlation of the local lift forces to the total lift force.

In order to study the Reynolds number effect on vortex resonance of streamline-like bridge deck section,Reynolds number was changed by adjusting scale of model,and pressure taps were set on the surface of model.Amplitude and wind pressure time history of two models were recorded.Reynolds number effect on vibration frequency spectrum,moment coefficient time history and fluctuation pressure frequency spectrum were studied.Intrinsic reasons of Reynolds number effect on vortex was revealed.The investigation indicates that Reynolds number effect on pressure spectrum cause the Reynolds number effect on moment coefficient time history and cause Reynolds number effect on vibration frequency spectum,lead to Reynolds number effect on vortex resonance of streamline-like bridge deck section.1 tab,9 figs,11 refs.

In order to study Reynolds number effect of Strouhal number of a bridge deck section,Reynolds number was changed by adjusting wind speed,and pressure taps were set on the surface of the model.Wind pressure time history was recorded with different Reynolds numbers.The varrying laws of pressure gradient,pressure coefficient power spectrum and frequency of vortex shedding were also studied with changes of Reynolds numbers.Reynolds number effect of Strouhal number was studied too.The investigation indicated that Reynolds number effect of the bridge deck pressure gradient and the pressure coefficient power spectrum is obvious,and it is difficult to identify vortex shedding by use of the frequency spectrum of pressure time-history record at high Reynolds number.Studies also showed that Reynolds number effect of Strouhal number exists in a bridge deck section.