On the allocation of city space to multiple transport modes

Abstract

This paper analyzes urban multimodal transportation systems in an aggregated way. To describe the aggregate behavior of traffic in cities, use is made of an idea that is now receiving some attention: the macroscopic fundamental diagram (MFD). We demonstrate through simulation how the MFD can be used to monitor and control a real network, in this case a portion of San Francisco, using readily available input data. We then show how different modes interact on the same network and discuss how these interactions might be incorporated into an MFD for multimodal networks. The work unveils two main results: first, it confirms recent results showing that restricting access to a city's congested areas can improve mobility for all travelers, including those who endure the restrictions; and second, that dedicating street space to collective transport modes can improve accessibility for all modes, even those from which space is taken away.     

科学史上关于寻找地外文明的争论——人类应该在宇宙的黑暗森林中呼喊吗?

尽管地外文明是否存在的问题,目前尚无定论,但与其相关的探讨,已成为科学史领域的重要研究课题。1970年代,随着搜寻地外文明计划（简称SETI）的一无所获,与其相对的另一种试图接触地外文明的实践手段——主动向地外文明发送讯息（简称METI）,也被提上日程,并在科学界引发颇多争议。本文对争论双方的观点以及争论所产生的影响进行了考察,并研究了与MET1有若的几种费米佯谬的解决方案。本文认为,在尚未做好接触地外文明的准备之前,实施MET1是非常危险的。     

平溃散治疗胃溃疡的作用机制研究

目的　探讨平溃散对胃溃疡的治疗作用和机制。方法　分别用组胺、乙醇及消炎痛诱发急性胃溃疡模型 ,观察平溃散对胃粘液 -碳酸氢盐屏障功能、胃液 pH值和胃跨膜电位的影响。结果　 2～ 4 g·kg-1的平溃散作用组溃疡指数下降 ,胃液 pH值和粘液含量增加 ,与对照组比较差异有显著性意义 (P <0 .0 5 ,P <0 .0 1,P <0 .0 1)。平溃散对乙醇引起的胃跨膜电位降低的抑制作用和模型组比较无显著性差异 (P >0 .0 5 )。结论　平溃散对胃溃疡具有良好的治疗作用 ,主要通过保护胃粘膜、抑制胃酸发挥作用     

Spatial and Temporal Variability in Shipping Traffic Off San Francisco,California

Shipping traffic poses a worldwide threat to many large whale species. Spatially explicit risk assessments are increasingly being used as a tool to minimize ship-strike risk. These assessments often use static representations of shipping patterns. We used Automatic Identification System data to quantify variability in cargo shipping traffic entering and exiting San Francisco Bay, which contains some of the busiest ports in the United States, at three temporal resolutions: (1) before and after implementation of the California Air Resources Board's Ocean-Going Vessels Fuel Rule, (2) among seasons, and (3) day versus night. We used the nonparametric Mood's Median test to compare median daily distance traveled because the data were not normally distributed and the variance was not homogeneous. Our analyses show that shipping traffic off San Francisco is dynamic at both interannual and daily temporal resolutions, but that traffic was fairly consistent among the seasons considered. Our analyses emphasize the importance of economic and regulatory drivers on interannual shipping traffic patterns. Shipping traffic is expected to continue to change off the U.S. West Coast and to increase globally. These changes in shipping traffic could have implications for the risk of ships striking whales and should be included in risk assessments.     

福建三都澳开展集装箱运输的战略问题

通过对宁德港三都澳港区建设条件、港口建设与地方经济发展、港口定位和集装箱运输需求,及其相互关系的分析,提出了三都澳港区的发展方向、起步工程规模和建设方案,以及开展工作的建议。     

基于手机数据的城市交通大区OD分布估计 ——以旧金山市为例

在大数据时代,手机数据因普及率高、采集成本低等优点逐渐受到人们的重视.手机通信运营商在为手机用户提供通信服务的同时会记录每次服务的时空信息,因此利用手机数据可以挖掘出用户的位置信息,并应用于城市居民出行OD分布估计.提出以手机数据为基础对城市交通大区之间OD分布进行估计的方法.利用居民手机数据估计美国旧金山市各交通大区之间的出行分布,并结合居民出行调查数据对估计结果进行检验.结果显示基于手机数据的出行估计具有较高的可靠性.     

美国旧金山湾区捷运系统

介绍美国旧金山湾区捷运系统(Bay AreaRapid Transit System,BART)。论述在旧金山湾区使用BART的重要意义,然后从现有线路、拟建线路规划等方面介绍该线路的总体情况,并对BART的车辆性能以及列车控制系统进行说明,最后分析BART在车票、换乘、环保和安全方面的优势。     

澜沧江三道拐河段航道整治模型试验研究

论述了三道拐河段河床复杂地形、碍航原因等情况,在认识滩性的基础上进行工程对比试验,提出了治理应以增大弯道半径和改善水流流态为主,从而保证中、枯水通航