In situ colonization of marine biofilms on UNS S32760 duplex stainless steel coupons in areas with different water qualities: Implications for corrosion potential behavior

In the presence of biofilms, stainless steels （SS） exhibits an increase in corrosion potential, called ennoblement. In the present study, the corrosion potential （Eco,） behavior of the duplex SS UNS S32760 was recorded simultaneously with the in situ marine biofilm formation in two areas at Arraial do Cabo, Southeastern Brazil. The biofilm at Forno Harbor （an anthropogenically disturbed area） was characterized by higher relative abundances of Bacteria at day 2, followed by diatoms （especially Navicula sp.） on day 10 and dinoflagellates on day 18, whereas no clear trend was recorded at Cabo Frio Island （an undisturbed area）. The ennoblement of Ecor values was site-dependent. In a complementary laboratory assay, biofilms were removed and the Eco values registered in sterile conditions for the subsequent 10 days and corroborated in situ results. Understanding biofilms and SS interactions has important implications for materials science and engineering decisions as well as helping to fill in imnortant gaps in this knowledge.     

汽车筒式液阻减振器技术的发展

分析了汽车乘坐舒适性／行驶平顺性和操作稳定性对筒式液阻减振器特性的要求，提出汽车在不同行驶工况减振器特性的要求是不的；分析了被动式减振器的发展历程及非充气和充气减振器的特点，阐述了机械控制式可调阻尼减振器，电子控制式减振器以及电流变和磁流变液体减器等的结构特点，工作原理及其动态特性；分析了筒式液阻减振器其于经验设计／实验修正开发方法的缺点，阐述了基于CAD／CAE技术的现代设计开发方法的过程及其关键问题，最后分析了我国筒式液阻减振器技术的发展状况及问题，展望了减振器技术的发展前景。     

Evaluation of forced flows on freeways with single‐loop detectors

This paper documents the development of a simple method for identifying and/or predicting freeway congestion using single loop detection systems. The proposed algorithm is simple and easy to incorporate into most freeway management systems. The Washington State Department of Transportation's Traffic Systems Management Center (TSMC) sponsored the original study. The investigation also led to a recommendation to replace the original TSMC definition of congestion or forced flow conditions with a more reliable indicator. Although, the TSMC has recently implemented a more advanced prediction system based on fuzzy set theory and neural networks to further identify patterns and rules for ramp metering strategies, the findings presented here continue to be constructive to freeway managers looking for quick and easy analyses that rely solely on single‐loop detection systems. The Seattle Area freeway study section used for the original study was the portion of mainline 1–5 northbound starting at the downtown Seattle Station 108 and ending at the Mountlake Terrace Station 193. Several days' worth of volume and lane‐occupancy data were collected for the afternoon time period from 2:30 p.m. to 6:30 p.m. Time intervals of 20 seconds were chosen for each data collection period. Important products of this research include the following:

• simple, and more reliable criterion for the definition of “bottleneck” or forced flow conditions than that originally used by the TSMC.
• simple, and reliable criterion for predicting impending “bottlenecks” or forced flow conditions.
• A proposed variable for improved selection of the appropriate metering rate. (Further analysis of the use of this variable for determining metering rates is recommended for future studies.

The proposed criteria are simple and easy to incorporate into current freeway management computer systems. Further investigation of freeway performance measurement using volume and occupancy data obtained from single‐loop systems is currently being performed.     

The stability of stochastic equilibrium in a two-link transportation network

Most research and applications of network equilibrium models are based on the assumption that traffic volumes on roadways are virtually certain to be at or near their equilibrium values if the equilibrium volumes exist and are unique. However, it has long been known that this assumption can be violated in deterministic models. This paper presents an investigation of the stability of stochastic equilibrium in a two-link network. The stability of deterministic equilibrium also is discussed briefly. Equilibrium is defined to be stable if it is unique and the link volumes converge over time to their equilibrium values regardless of the initial conditions. Three models of route choice decision-making over time are formulated, and the stability of equilibrium is investigated for each. It is shown that even when equilibrium is unique, link volumes may converge to their equilibrium values, oscillate about equilibrium perpetually, or converge to values that may be considerably different from the equilibrium ones, depending on the details of the route choice decision-making process. Moreover, even when convergence of link volumes to equilibrium is assured, the convergence may be too slow to justify the standard assumption that these volumes are usually at or near their equilibrium values. When link volumes converge to non-equilibrium values, the levels at which the volumes stabilize typically depend on the initial link volumes or perceptions of travel costs. Conditions sufficient to assure convergence to equilibrium in two of the three models of route choice decision-making are presented, and these conditions are interpreted in terms of the route choice decision-making process.     

融合可持续理念的交通规划方案比选方法——以亚特兰大大都市区为例

越来越多的机构开始为交通系统的可持续发展定义,并试图将这一概念融入区域交通规划过程.然而,只有极少数的区域规划机构意识到了交通系统和土地利用变化给经济、环境和社会生活质量(这三者通常被认为是可持续交通系统的三个基本方面)带来的广泛影响.首先,论述了使用多个可持续发展指标的多准则决策方法,并应用其评估亚特兰大大都市区的三...     

3D brush model to predict longitudinal tyre characteristics

A 3D tyre brush model, which aims to predict the longitudinal tyre characteristic under steady-state conditions by modelling the occurring physical effects in the tyre–road contact patch, is presented. The model includes an analytical method to describe the tyre footprint geometry, the pressure distribution, the slip due to the lateral tyre contour, the slip due to braking or traction and the longitudinal as well as the lateral shear stresses on a flattened tyre. The presented development tool offers a method to investigate different rubber friction data (caused by different tread compounds and/or surface textures) and to analyse its influence on longitudinal tyre characteristics. The tyre design is fixed (same casing, dimension and pattern). The results include the shear stresses as well as the different sliding velocities in the contact patch for different slip conditions. The model was developed for a standard summer pattern design and a standard tyre dimension (205/55R16). It can also be adapted to other tread designs and tyre dimensions. To offer a good comparability between model results and test bench measurements, the surface curvature of an internal test rig is considered.     

Route choice of cyclists in Zurich

This paper presents the first route choice model for bicyclists estimated from a large sample of GPS observations and overcomes the limitations inherent in the generally employed stated preference approach. It employs an improved mode detection algorithm for GPS post-processing to determine trips made by bicycle, which are map matched to an enriched street network. The alternatives are generated as a random sample from an exhaustive, but constrained search. Accounting for the similarity between the alternatives with the path-size factor the MNL estimates show that the elasticity with regards to trip length is nearly four times larger than that with respect to the share of bike paths. The elasticity with respect to the product of length and maximum gradient of the route is small. No other variable describing the routes had an impact. The heterogeneity of the cyclists is captured through interaction terms formulated on their average behaviour.     

公路桥梁维修加固的方法探讨

随着交通运输事业的快速发展,过去修建的桥梁,承受着大量超载车辆和超大交通量的沉重负荷,出现了各种各样的病害.根据近年对公路桥梁的维修加固实践,总结了一些公路桥梁的病害及维修加固的方法.