Safety modeling for two‐way left‐turn lanes and a procedure to identify two‐way left‐turn lane segments with safety concerns

In the past, two‐way left‐turn lane (TWLTL) median treatments have been frequently used in Florida to inexpensively improve traffic and safety performances. In order to identify factors that may have significant impacts on safety operations in TWLTL sections and to identify TWLTL locations that present existing and future safety concerns, a research project was carried out and results are summarized in the paper. In the research, a three‐year crash history database with crashes and section characteristics from a total of 1688 TWLTL sections all over Florida was developed and used. A negative binomial regression model was developed to determine the statistical relationship between the number of crashes per mile per year and several variables such as traffic volume, access density, posted speed, and number of lanes. In regard to the methodology, in order to identify locations with safety concerns, several steps are needed: development of real crash data distribution, determination of statistical distribution models that better represent the actual crash data, determination of percentile values for the average number of crashes, estimation of crash rates for sections with the same characteristics, estimation of critical values for the variables corresponding to the percentile values for average number of crashes, calculation of tables of critical average annual daily traffic values, and generation of a list of TWLTL locations with critical safety concerns. Results presented in the paper have been used in real applications. Copyright © 2012 John Wiley & Sons, Ltd.     

浅谈城市轨道交通建设项目水土保持防治措施

以上海市徐汇区某轨道交通工程项目为例,围绕工程及项目特点,展开分析了该类型生产项目建设的水土流失特点及防治分区特征,并对水土保持措施进行总体布局,以确保城市轨道交通项目水土保持防治措施全面有效地发挥作用.     

Carrier冷藏集装箱微电脑控制器排气压力故障排除

通过对CARRIER冷藏集装箱排气压力故障的分析,阐述修理冷藏集装箱微电脑控制器的一般分析方法、测试方法及应注意问题。     

地下连续墙的受力状态及计算图式分析

在地下连续墙工程现场观测的基础上,对其受力状态进行了分析探讨。指出单元墙段是呈双向弯曲受力状态。因而按现行设计(单向受弯)的配筋计算应做适当的调整。在用筋总量不增加的基础上,使墙体结构设计更加合理、完善、经济、可靠。     

Hydrographic cruises off northwest Africa: the Canary Current and the Cape Ghir region

We present hydrographic data for several sections located along the African coastline and off Cape Ghir, carried out at times of weak surface winds (October 1995 and September 1997). The main sections are near the continental slope, at mean distances between 100 and 150 km from the coastline. North of Cape Ghir (31°N) the geostrophic transport (referenced to 650 m) of North Atlantic Central Water through these sections is 3.7 and 2.0 Sv for 1995 and 1997, respectively. This confirms that a major fraction of the water transport by the Canary Current flows east, into the continental slope off northwest Africa, at latitudes above Cape Ghir. Most of this flow continues south past Cape Ghir, along the coast and probably through the eastern passages of the Canary Archipelago. A significant fraction, however, may escape through surface Ekman transport (0.3–0.5 Sv during the early fall season) and by offshore flow at Cape Ghir (1.1 Sv in September 1997, referenced to 650 m). Despite the weak winds the Cape Ghir filament was clearly visible, characterized by localized coastal upwelling associated to a cyclonic shallow structure and cold (and fresh) waters stretching offshore as a very shallow feature (50–100 m deep). The satellite images show that the surface temperature field is highly variable, in rapid response to the surface winds, always with a core region of relatively cold water and commonly with one or two associated eddies. Our results support the existence of two recirculation cells in the area: a horizontal one that connects the interior eastern boundary currents with the coastal region and a vertical one related to both wind-induced and filament upwelling. The data also show a salinity subsurface maximum at the root of the filament, linked to water inflow from northern latitudes, and a subsurface anticyclonic eddy over the Agadir canyon, likely related to the poleward slope undercurrent.     

A practical assessment of stated preferences methods

Stated preferences data in the form of rankings, ratings and choices were collected in Santiago and discrete choice models estimated with them. The models were compared in terms of accuracy v/s the cost of obtaining the information and models. All methods produced reasonable but different models and fairly close subjective values of time. In terms of production costs the ranking method was a clear looser although the experimental design was slightly biased against it. Finally, the use of computerised interviews is highly recommended particularly for dealing with low income people.     

基于模糊时间Petri网的列车运行时间不确定性问题的处理

定义一种应用于铁路列车运行系统的模糊时间Petri网；针对列车运行时间存在的不确定性，该Petri网引入了4个模糊集理论函数：模糊时间片、模糊使能时间、模糊发生时间和模糊延迟，来处理时间的不确定性问题；能够对列车运行过程中的时间不确定性问题进行定量分析，可以有效应用于列车交会、列车终到时间、列车运行计划调整的分析等；其相对于已有的方法具有精确分析、计算简单、简化系统、便于系统集成的特点。     

基于NAPA大宽深比船舶总纵强度计算方法及分析

以大宽深比船舶为研究对象，根据梁理论基本原理，以某近海油船为实例，提出一套基于船舶设计软件NAPA进行总纵强度计算方法和步骤。并与传统手工计算结果相比较，结果表明该方法比传统方法具有较高的计算精度和效率。     

球形破片侵彻金属靶板的数值模拟研究

利用三维非线性有限元软件LS-DYNA对球形破片在不同速度以及不同入射角度下侵彻金属薄板的过程进行模拟,得出破片的极限穿透速度、剩余速度、剩余质量以及靶板的破坏模式等结果信息,总结出侵彻性能与破片初速度以及入射斜角的关系,以期能够为工程设计以及军事应用提供依据。     

A week in the life of baby boomers: how do they see the spatial–temporal organization of their activities and travel?

In this paper, we take an initial look at the spatial and temporal flexibility in the activity patterns of the so-called “baby-boomer” cohort (born 1947–1966) in comparison with younger and older adults. Using a unique longitudinal survey carried in Quebec City from 2002 to 2005, we explore activity patterns and trip rates over a seven-day observation period during the first wave, and take a first look at some aspects of their evolution over two subsequent waves at about one-year intervals. We model the propensity to undertake activities within selected conventional non-work classifications such as “shopping” and “leisure”, and also according to respondents’ own perceptions of the spatial and temporal flexibility of each out-of-home activity that they had executed. While we cannot strictly separate cohort effects from age-related effects, after controlling for gender and household structure, we infer that age and related lifestyle effects dominate in explaining these propensities. However, the boomers were the only age stratum to increase their total out-of-home activity participation over the course of the panel, an intriguing starting point for the future study of this cohort.