高掺量粉煤灰碾压混凝土路用力学性能的研究

通过对高掺量粉煤灰碾压混凝土的力学性能的测试和对其中粉煤灰掺量的影响及提高水泥标号对粉煤灰激发效果的机理分析,得出以下结论;高掺量粉煤灰碾压混凝土的早期强度随粉煤灰掺量的提高呈下降趋势,但随龄期增长幅增大;提高粉煤灰掺量有利于降低碾压混凝土的脆性;提高水泥标号对高掺量粉煤灰碾压混凝土的早期强度有利,但降低了抗折强度的后期增幅。     

钢筋混凝土预制空心板构件早期裂缝的试验研究

通过一座公路桥梁施工过程中一批钢筋混凝土预制空心板构件出现早期裂缝的工程实例,分析了裂缝产生的原因,结合荷载试验的实测结果,说明了早期裂缝对桥面板结构性能的影响,为今后判断具有同类裂缝缺陷的预制薄壁构件能否满足两种极限状态的设计要求提供了有参考价值的技术依据。     

停车设施规划方案的多指标评价方法

从分析城市停车设施评价指标出发,深入研究各评价指标的内容及计算方法,在此基础上提出决策矩阵的标准化以及综合的多指标决策评价方法,不仅可用于评价城市现状停车设施总体状况,而且为决策人员进行规划年停车方案的比选提供良好的辅助工具,算法在上海市浦东新区停车场的规划与评价中得到很好的应用。     

城市交通系统降低燃油消耗的重要性分析

城市交通系统燃油消耗是造成城市环境恶化的主要污染源之一,城市交通的发展必然会使得燃油消耗增加、环境恶化,更重要的是制约了城市经济的发展,文章提出了降低城市交通系统燃油消耗的主要措施,全面阐述了降低交通系统燃油消耗与城市经济可持续发展的关系。     

基于合作竞争类OD的轨道客流预测方法研究

在分析基于全方式ＯＤ采用联合方式划分交通分配模型进行轨道客流预测不足的基础上,提出了一种基于合作竞争类ＯＤ的采用联合方式划分交通分配模型的轨道交通客流则方法,即由出行产生和分布预测得到全方式的ＯＤ矩阵,通过分层次策略性交通方式划分法得到合作竞争类出行ＯＤ矩阵,然后采用联合方式划分交通分配模型进行轨道线网客流预测。     

公交线路客流模糊神经网络预测模型

提出一种基于模糊神经网络理论的公交线路客流预测模型。实验比较发现,该模型具有较强的自适应性,其预测结果优于常规时间序列模型ＡＲ、ＡＲＭＡ得到的预测结果。该模型适用于公交企业运营调度管理的需要。     

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.     

A conceptual and methdological framework for the generation of activity-travel patterns

This paper develops a conceptual framework for the generation of activity and travel patterns in the context of more general structures and presents an integrated model system as a step toward development of an improved travel demand forecasting model system. We propose a two-stage structure to model activity and travel behavior. The first stage, the stop generation and stop/auto allocation models, consists of the choices for the number of household maintenance stops and the allocation of stops and autos to household members. The second stage, the tour formation model, includes the choices for the number of tours and the assignment of stops to tours for each individual, conditional on the choices in the first stage. Empirical results demonstrate that individual and household socio-demographics are important factors affecting the first stage choices, the generation of maintenance stops and the allocation of stops and autos among household members, and the second stage choices, the number of tours and the assignment of stops to tours. This revised version was published online in June 2006 with corrections to the Cover Date.     

Fatigue damage calculation for oil tanker and container ship structures

The fatigue behaviour of longitudinal stiffeners of oil tankers and container ships, subjected to dynamic loads, is analysed. The following dynamic load components are considered: hull girder vertical wave bending moment, alone and combined with the horizontal wave bending moment, hydrodynamic pressure and inertial forces caused by cargo acceleration.

The spectral method was selected to calculate the fatigue damage, based on S—N curves and Miner's rule. Following this approach, the fatigue damage may be calculated as a function of a stress parameter Ω_p, which represents the cumulative effect of wave induced loads in the unit of time and incorporates the combined effects of stress level and its occurring frequency.

Simple formulas for Ω_p of oil tankers and container ships are given, obtained from the results of hydrodynamic analyses performed on several ships, in different wave environments.

Several examples show the applicability of the methods to real ship structures. The method, however, still needs to be calibrated because of the simplifying hypotheses introduced in the loading conditions.