A disaggregated tool for evaluation of road safety policies

This paper presents a methodological disaggregated approach to analyze the impact of interventions on road safety. The model aims to describe the accident rates of an individual using mileage as a measure of risk exposure. The model is formulated as a system of equations that takes into account interactions between the mileage of a given individual and the other drivers. Once estimated, the model acts as a simulator allowing us to measure the performance of policy interventions to increase road safety.     

Comparison of particle mass and number emissions from a diesel transit bus across temporal and spatial scales

This study analyzes particle number and mass emission rates measured from the exhaust of a 2002 diesel transit bus in real-world driving conditions. The dynamics of the particle number and mass emission rates are examined at resolved temporal and spatial scales across an urban arterial, a rural arterial and a divided freeway. Time-based particle number and mass emission rates were highest on the freeway, but the distance-based particle emission rates of emission/km at “hot-spots” for exposure assessment for selected 50-m road segments occurred at intersections when the bus accelerated from a stop or traveled up high grades. Comparisons of particle mass and number emission rates between idling and acceleration indicate that unless the bus is extending idling for several minutes, public exposure to bus particle emissions near bus stops can be mainly attributed to accelerations. Generally, particle number and mass emissions rates are highly correlated both temporally and spatially. Some deviations occur because particle mass emissions are highly elevated during sustained fueling events such as traveling on high grades and during sustained accelerations, while particle number emissions are more sensitive to fuel and engine speed fluctuations.     

Bayesian updating of trip generation data: Combining national trip generation rates with local data

With traffic impact analyses and impact fee assessment becoming more popular, the need for accurately estimating the trip generation rate of a proposed development is becoming more important. An overwhelming percentage of state transportation agencies depend either partly or entirely on the ITETrip Generation Report to predict the traffic that will be attracted to and/or produced from a proposed development. However, the rates obtained from the ITE publication have been derived from data collected throughout the United States. They represent a national average and fail to take into account the local trip generation characteristics that the site under consideration might have. This paper establishes a methodology for obtaining more reliable local trip generation rates using Bayesian statistics. In this method, the ITE rates are assumed to be the prior information, which are updated using limited local trip generation data that are available. The method also allows for temporal updating, incorporating subjective judgment and using borrowed data in the updating procedure. Sample calculations in this paper illustrate the developed methodology.     

Examining the theoretical–empirical inconsistency on stationarity of shipping freight rate

As market price, shipping freight rates should in theory be stationary, but most empirical tests have found them to be non-stationary. To examine the causes of this theoretical–empirical inconsistency, we investigate the sensitivities of the stationarity of shipping freight rates from two perspectives: sample length and sample window. Longer samples are found not sufficient to make them stationary. Instead, sample windows separated by structural breaks are tested as stationary. Moreover, freight rates are found to have entered into a new phase since the 2008 financial crisis. This study contributes to the literature on the stationarity of shipping freight rates by providing an explanation for the theoretical–empirical inconsistency.     

级配钢纤维活性粉末混凝土的动态拉伸性能的试验研究

采用分离式Hopkinson压杆(SHPB)对直径为70 mm的圆柱体试件的动态拉伸性能进行研究,得到了不同应变率下的混凝土劈裂拉伸强度和拉伸应力-时间曲线,并与静态劈裂拉伸强度进行了对比。根据试验结果,讨论了含不同种类钢纤维的活性粉末混凝土的动态拉伸性能,以及3种钢纤维级配下的钢纤维活性粉末混凝土的动态拉伸性能;总结了级配钢纤维活性粉末混凝土的应变率效应,以及影响钢纤维混凝土动态拉伸性能的因素。     

锈蚀钢绞线力学性能的试验研究

利用电化学快速锈蚀方法获得了混凝土中不同锈蚀程度的钢绞线,并得到了裂缝宽度与锈蚀重量损失率之间的关系。通过静拉伸试验数据的回归分析得出名义极限强度、名义弹性模量和极限延伸率的降低与锈蚀重量损失率之间的关系。     

关于对公路基本建设工程投资估算、概算、预算编制办法中部分取费标准的探讨

交通部1996年《公路基本建设工程投资估算编制办法》和《公路基本建设工程概算、预算编制办法》中的部分取费规定已不符合公路基本建设工程的实际情况,急需进行修订。     

成像侦察卫星及其对抗技术浅析

成像侦察卫星在现代信息作战中发挥了越来越突出的作用。文章首先分析了成像侦察卫星的分辨率,其获取信息的能力形成了对敌方强大的威胁,具有为决策和制定作战行动计划提供依据和为精确打击目标提供保证的现实军事意义。最后针对成像侦察卫星的可对抗性,提出主动攻击和被动防护两种对抗措施,并对其进行了具体地阐述。     

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分析原油价格对油轮运价指数的影响关系,并预测油轮运价指数发展变化趋势.本文通过Granger因果关联分析,原油价格是油轮运价指数的3阶Granger因.因此,建立了3阶ARCH模型对油轮运价指数进行了预测,预测精度在8%之内.根据油轮运价指数的自身非线性变化趋势,建立了三层BP神经网络模型预测油轮运价指数的发展趋势,精度在3%以内.为进一步提高模型的预测精度,结合ARCH预测模型和BP神经网络预测模型的特点,通过预测误差最小化模型,确定组合权重,建立了新的组合预测模型对未来油轮运价指数进行分析预测,模型的精度控制在2%以内,预测精度显著提高.此研究对油轮运价指数的预测提供了较好的方法.     

金融期货对推进利率市场化的作用研究

分析了我国金融期货市场及利率市场化改革发展的现状,研究了金融期货发展对利率市场化改革的作用。