On a link-based day-to-day traffic assignment model

In this paper, we perform a rigorous analysis on a link-based day-to-day traffic assignment model recently proposed in He et al. (2010). Several properties, including the invariance set and the constrained stability, of this dynamical process are established. An extension of the model to the asymmetric case is investigated and the stability result is also established under slightly more restrictive assumptions. Numerical experiments are conducted to demonstrate the findings.     

广西高速公路生态环境保护对策研究

文章针对广西高速公路生态环境现状,分析当前高速公路环境保护工作中存在的问题,从生态学角度提出了高速公路沿线生态环境建设和保护对策。     

基于分级节点的高速铁路货运动车组开行研究

“八纵八横”高速铁路网货运节点可以利用聚类分析法,依据货运总量、GDP、人口、社会消费品零售总额、快递业务量、线路连接数、城市类别和节点类别等指标划分为4个等级。基于灰色系统预测模型,预测2025年高速铁路货运量,构建数学模型计算保本货运量。依据节点划分、货运量预测、保本货运量结果,计算各等级节点中盈利OD所占的比例,结合日均OD量,分析各等级节点间开办高速铁路货运的可行性。研究表明,在一级节点之间可以开行高速铁路货运动车组专列,在二级节点之间可以开行客货联挂动车组,三、四级节点可以采用捎带运输的方式。     

含软弱土层边坡稳定性分析的全局滑面自动搜索技术

提出了一种用于边坡稳定性分析的全局滑面自动搜索技术,首先采用三角网格进行了边坡土层的几何离散,然后,结合蒙特卡洛法等角/等边逐段扫描与模拟退火法,构建了全套的边坡全局临界滑面搜索扫描算法。以Fortran和Matlab为计算手段进行联合编程,采用简明Morgenstern-Price法进行了边坡稳定性分析计算。通过选用3个算例进行了算法的可靠性验证,计算结果表明:截面三角网格划分方法具有良好的适应性,能较好地对不规则层位几何形状进行离散;多段折线滑面具有较圆弧滑面更为优秀的极限滑面定位功能,其安全系数随着滑面段数的增加会逐步达到收敛;本搜索方法可不依赖于工程师经验进行多段折线初始滑面的大致范围选择,其能快速地、全自动地进行由弱到强不同复杂土质情况的边坡稳定性计算分析,并能找到全局临界滑面与安全系数。     

GSM-R中跨SGSN更新时源SGSN域名解析数据的智能生成方案设计

源SGSN域名解析数据是GSM-R网络编号方案数据中重要的需跨局制作的一类数据。由RAI编码构造生成,在跨SGSN路由区更新时,存储于DNS中,以解析源SGSN的IP地址。全路400多条G网线路,错综复杂的基站引用关系,导致数据复杂多样。针对该情况,利用聚类分析和关联规则分析算法,研究源SGSN解析数据的智能生成方案,提高数据的全面性、准确性,从而有效保障GSM-R分组域应用业务的正常运转。     

Turn taking behavior in dual earner households with children: a focus on escorting routines

Transportation - This article discusses results of a study on turn taking behavior in escorting children in dual-earner households. Using a multinomial logit model, the probability of different...     

2019年国际海事组织大事记

2019年对于国际海事组织(IMO)来说是充满挑战、富有成效的一年,其工作成果覆盖了海上航行安全、海上环境保护、海上便利运输等各个领域,并且在“为海事界女性增权赋能”方面开展了扎实的工作。本文对2019年IMO的各项工作成果简要回顾如下:一、海上航行安全(一)渔船安全公约批约获得重大进展10月21日至23日,主题为“渔船安全和打击非法、未报告及无管制(IUU)捕捞”的部长级会议在西班牙举行。会议由西班牙政府、联合国粮农组织(FAO)和皮尤慈善信托基金会联合主办,来自120个国家和30个国际组织的约70名部长级代表及约500名代表参加了会议。     

Activity involvement and time spent on computers for leisure: an econometric analysis on the American Time Use Survey dataset

Internet is capturing more and more of our time each day, and the increasing levels of engagement are mainly due to the use of social media. Time spent on social media is observed in the American Time Use Survey and recorded as leisure time on Personal Computer (PC). In this paper, we extend the traditional analysis of leisure activity participation by including leisure activities that require the use of a PC. We study the substitution effects with both in-home and out-of-home leisure activities and the time budget allocated to each of them. The modeling framework that includes both discrete alternatives and continuous decision variables allow for full correlation across the utility of the alternatives that are all of leisure type and the regressions that model the time allocated to each activity. Results show that there is little substitution effect between leisure with PC and the relative time spent on it, with in-home and out-of-home leisure episodes. Households with more children and full-time workers are more likely to engage in in-home and PC related leisure activities (especially during weekends). Increments in the travel time of social trips result in significant reductions in leisure time during weekdays.     

隧道开挖中的应力旋转和裂隙塑性变形问题研究

通过对隧道开挖过程进行三维数值模拟,分析了隧道开挖过程中主应力方向的旋转变化,研究了主应力旋转与隧道裂隙塑性变形的关系,验证了"考虑应力主轴旋转的广义塑性原理"的正确性,并将数值模拟结果和相关试验成果进行了对比,得出了一致性的结论。研究结果表明,应力旋转基本在隧道开挖前后10 m左右的距离内完成,隧道开挖过程中的应力旋转可以引起裂隙塑性变形的突变,且对竖向和斜向裂隙的影响较大;可以根据应力旋转的变化规律合理地选择支护时机,依据应力旋转对裂隙的影响对隧道的重点部位进行超前加固。