Analyzing spatiotemporal traffic line source emissions based on massive didi online car-hailing service data

Nowadays, the massive car-hailing data has become a popular source for analyzing traffic operation and road congestion status, which unfortunately has seldom been extended to capture detailed on-road traffic emissions. This study aims to investigate the relationship between road traffic emissions and the related built environment factors, as well as land uses. The Computer Program to Calculate Emissions from Road Transport (COPERT) model from European Environment Agency (EEA) was introduced to estimate the 24-h NOx emission pattern of road segments with the parameters extracted from Didi massive trajectory data. Then, the temporal Fuzzy C-Means (FCM) Clustering was used to classify road segments based on the 24-h emission rates, while Geographical Detector and MORAN’s I were introduced to verify the impact of built environment on line source emissions and the similarity of emissions generated from the nearby road segments. As a result, the spatial autoregressive moving average (SARMA) regression model was incorporated to assess the impact of selected built environment factors on the road segment emission rate based on the probabilistic results from FCM. It was found that short road length, being close to city center, high density of bus stations, more ramps nearby and high proportion of residential or commercial land would substantially increase the emission rate. Finally, the 24-h atmospheric NO₂ concentrations were obtained from the environmental monitor stations, to calculate the time variational trend by comparing with the line source traffic emissions, which to some extent explains the contribution of on-road traffic to the overall atmospheric pollution. Result of this study could guide urban planning, so as to avoid transportation related built environment attributes which may contribute to serious atmospheric environment pollutions.     

Public service obligations for air transport in the United States and Europe: Connectivity effects and value for money

Public service obligations (PSOs) are used by governments in many countries, including the United States and 11 countries in Europe, to mandate a minimum level of commercial air transportation service, especially for small or rural communities. This paper analyzes PSOs in these 12 countries for the year 2010 using the recently proposed Global Connectivity Index to measure direct and indirect market access and a novel subsidy database covering 90% of PSO movements in these countries to assess value-for-money.We show that PSO services represent about 2.5% of all commercial movements in the 12 countries analyzed, generating about 1% of these countries’ total air transport connectivity. Over all routes for which data was available, approximately USD$ 900 million was earmarked for PSO and air service discount provision in 2010, with average subsidies per movement ranging from about $700 to $3500. PSO market access and efficiency outcomes vary across the countries analyzed. Some countries, such as Germany and the United States, focus on providing network access for smaller communities, thereby creating not only point-to-point, but also onward connectivity, while others such as Norway, Sweden, and Ireland, predominantly aim at providing “lifeline services” that connect remote regions to a nearby economic center without providing onward connections.     

Optimization of periodic crew schedules with application of column generation method

We present an alternative approach to the problem of periodic crew scheduling. We introduce the concept of frames which leads us to a modeling approach which suits well the current practice of the majority of European railway operators. It results in a model facilitating column generation techniques resulting in a Dantzig-Wolfe type decomposition, and thus suitable for a parallel implementation in a high-performance computing environment. We exploit the properties of network flow models to avoid several additional integer constraints. We compare two approaches to solve the problem. The first approach consists of solving the original problem by single model. The second approach is our step-by-step column generation. The comparison is based on our implementation which we describe in detail along with its application to certain benchmark instances. The benchmarks originate in real or close-to-realistic problems from railway systems in Slovakia and Hungary. The case studies demonstrate that our model is well-suited for real-life applications.     

Designing an integrated distribution system for catering services for high-speed railways: A three-echelon location routing model with tight time windows and time deadlines

An emerging task in catering services for high-speed railways (CSHR) is to design a distribution system for the delivery of high-quality perishable food products to trains in need. This paper proposes a novel model for integrating location decision making with daily rail catering operations, which are affected by various aspects of rail planning, to meet time-sensitive passenger demands. A three-echelon location routing problem with time windows and time budget constraints (3E-LRPTWTBC) is thus proposed toward formulating this integrated distribution system design problem. This model attempts to determine the capacities/locations of distribution centers and to optimize the number of meals delivered to stations. The model also attempts to generate a schedule for refrigerated cars traveling from distribution centers to rail stations for train loading whereby meals can be catered to trains within tight time windows and sold before a specified time deadline. By relaxing the time-window constraints, a relaxation model that can be solved using an off-the-shelf mixed integer programming (MIP) solver is obtained to provide a lower bound on the 3E-LRPTWTBC. A hybrid cross entropy algorithm (HCEA) is proposed to solve the 3E-LRPTWTBC. A small-scale case study is implemented, which reveals a 9.3% gap between the solution obtained using the HCEA and that obtained using the relaxation model (RM). A comparative analysis of the HCEA and an exhaustive enumeration algorithm indicates that the HCEA shows good performance in terms of computation time. Finally, a case study considering 156 trains on the Beijing-Shanghai high-speed corridor and a large-scale case study considering 1130 trains on the Chinese railway network are addressed in a comprehensive study to demonstrate the applicability of the proposed models and algorithm.     

北京市定制商务班车乘客支付意愿研究

生活水平的极大提升导致居民对出行品质期望更高,因此对出行疲劳缓解和在途时间有效利用的考虑在交通服务质量改善的研究及措施中愈加不可回避。基于北京市定制商务班车乘客支付意愿调查,首先分析定制商务班车的线路特征和客流特征。其次,对比研究出行者选乘定制商务班车前后服务特性的差距,特别关注长距离出行者对出行疲劳、无效在途时间减少的支付意愿。结果表明,乘客放弃原有出行方式选择定制商务班车与这一服务所带来的体能消耗、无效在途时间节省呈现较高相关性,乘客愿意支付远高于当前公交票价的费用用于上述两方面的改善。最后指出,如能对当前服务模式稍作调整,接受一定比例的非预订座位乘客,高水平公交服务的受众群体将更为广泛。     

基于BP神经网络的城市公交服务质量影响因素主成分分析

为改善城市公交服务质量,根据乘客服务质量问卷调查数据分析,运用主成分分析方法对公交服务质量影响因素进行降维处理,把15个影响变量提取为8个主成分变量.在此基础上,运用MATLAB7.0建立影响因素主成分与公交服务质量认可度的BP神经网络模型,在不同参数下进行试验和比较,计算出模拟数据下公交服务质量认可度折减影响系数均方差为0.000 957,表明该模型所选参数值可以用于评估公交服务质量的影响因素分析.最后,根据权值和阀值计算得出影响城市公交服务质量的关键因素为公交车内拥挤程度、驾驶员服务态度和首末班车时间,其影响程度分别为53.09％、32.02％和30.36％.研究结论可以为城市公交服务质量改善提供依据并明确重点改进的方向.     

卫星导航系统服务性能分析与试验验证

北斗卫星导航系统已成为服务于中国及其周边地区的区域系统,并成为在轨运行的三大卫星导航系统之一。兼容互操作是卫星导航系统的发展趋势,为方便导航用户选星的使用要求,分析三大卫星导航系统的服务性能,给出卫星导航系统服务性能指标及定义。结合国内外学者对卫星导航系统服务性能的研究,对GPS、GLONASS和COMPASS等三大卫星导航系统的空间信号精度进行分析。结果表明我国北斗卫星导航系统在服务范围内能够向用户提供与GPS系统相同精度的定位、授时服务,且服务精度优于GLONASS系统。     

基于XML的海洋信息索引服务系统构建研究

海洋信息索引服务系统的关键在于需要有一套完备、科学的元数据格式,对各种海洋信息的格式、内容、意义等进行定义,使得能够对各种信息进行有效的解释和组织。本文以ISO 19115和DIF标准为依据,提出了一种基于XML的元数据格式定义方案,以XML为元数据定义描述语言,对各种海洋信息进行解释和定义,其具有较好的易用性和通用性。在此基础上,本文研究并构建了基于Web服务的海洋信息索引服务系统,经验证能够对海洋信息进行有效的存储和管理。     

基于“1+X”证书制度下高职人才培养模式研究与实践——以汽车技术服务与营销专业为例

目前我国高职汽车技术服务与营销人才培养存在对职业培训不够重视、产教融合深度不够、师资技能培训力度不够等问题。为了深入贯彻落实《国家职业教育改革实施方案》和《职业技能提升行动方案(2019-2021)》文件精神,稳步推进"学历证书+若干职业技能等级证书"制度试点工作,对培养新型汽车技术服务与营销应用型人才提出了更高的要求,基于这一背景,本文对完善高职汽车技术服务与营销专业人才培养模式提出了相应的措施和建议。     

广州地铁二号线通信系统设计的有关问题

研究目的:通过研究二号线通信系统设计的主要特点、主要技术创新以及开通后达到的效果,为我国城市现代大运量轨道交通线路通信系统的建设,提供工程设计经验和借鉴。研究方法:根据运营需求和通信技术的发展,从广州地铁二号线通信系统的组网技术、系统构成等方面进行多方案的比选研究。研究结果:提出了二号线通信系统的技术选择,组网构成,并使通信系统投资大为下降。研究结论:进行新线设计时,必须针对本线通信系统设计存在问题进行专题研究;构造并实施通信系统项目的全过程管理;在地铁通信系统UPS配备的蓄电池备电时间方面,建议对传输系统、无线系统、电话系统、中心一级母钟采用2~4 h备用,其它系统为1 h备用;在车辆段和地面区间,主干电(光)缆均敷设在电缆管道内,管道数量应按远期需要一次性设置;在多雨地区的人井处设置排水系统,并与车辆段主排水系统相通,可解决人孔积水问题。