Auction-based tolling systems in a connected and automated vehicles environment: Public opinion and implications for toll revenue and capacity utilization

Autonomous and connected vehicles are expected to enable new tolling mechanisms, such as auction-based tolls, for allocating the limited roadway capacity. This research examines the public perception of futuristic auction-based tolling systems, with a focus on the public acceptance of such systems over current tolling practices on highways (e.g., dynamic and fixed tolling methodologies). Through a stated-preference survey, responses from 159 road-users residing in Virginia are elicited to understand route choice behavior under a descending price auction implemented on a hypothetical two-route network. Analysis of the survey data shows that there is no outright rejection of the presented auction-based tolling among those who are familiar with the current tolling methods. While males strongly support the new method, no clear pattern emerges among other demographic variables such as income and education level, and age. While high income respondents and regular commuters are more likely to pay higher tolls, no statistical significance between different genders, age groups, household sizes, and education levels is found. Based on the modeling results and the hypothetical road network, it is found that descending price tolling method yields higher average toll rates, and generates at least 70% more revenue when travel time saving is 30 min, and improves capacity utilization of the toll road significantly compared to fixed tolls.     

The role of alternative fuel vehicles: Using behavioral and sensor data to model hierarchies in travel

Greater adoption and use of alternative fuel vehicles (AFVs) can be environmentally beneficial and reduce dependence on gasoline. The use of AFVs vis-à-vis conventional gasoline vehicles is not well understood, especially when it comes to travel choices and short-term driving decisions. Using data that contains a sufficiently large number of early AFV adopters (who have overcome obstacles to adoption), this study explores differences in use of AFVs and conventional gasoline vehicles (and hybrid vehicles). The study analyzes large-scale behavioral data integrated with sensor data from global positioning system devices, representing advances in large-scale data analytics. Specifically, it makes sense of data containing 54,043,889 s of speed observations, and 65,652 trips made by 2908 drivers in 5 regions of California. The study answers important research questions about AFV use patterns (e.g., trip frequency and daily vehicle miles traveled) and driving practices. Driving volatility, as one measure of driving practice, is used as a key metric in this study to capture acceleration, and vehicular jerk decisions that exceed certain thresholds during a trip. The results show that AFVs cannot be viewed as monolithic; there are important differences within AFV use, i.e., between plug-in hybrids, battery electric, or compressed natural gas vehicles. Multi-level models are particularly appropriate for analysis, given that the data are nested, i.e., multiple trips are made by different drivers who reside in various regions. Using such models, the study also found that driving volatility varies significantly between trips, driver groups, and regions in California. Some alternative fuel vehicles are associated with calmer driving compared with conventional vehicles. The implications of the results for safety, informed consumer choices and large-scale data analytics are discussed.     

高速公路沥青混凝土路面常见病害及防治

文章主要介绍了高速公路沥青混凝土路面常见的病害及产生原因,提出了早期预防措施和后期治理等。     

美海军DDG-1000全舰计算环境体系结构探析

  目的  现代舰艇灾害突发性以及蔓延快速性的显著提升,对舰艇损管指挥网络的信息化水平提出了更高要求。基于损管指挥信息系统复杂的网络特性分析,构建该系统的网络拓扑模型。  方法  针对当前模型存在的不足,在随机网络化方法的基础上,综合考虑损管指挥信息网络的节点属性和增加网络密度的成本因素,提出一种择优随机网络化的结构优化方法,并通过案例仿真对具体的优化流程予以演示。  结果  仿真结果表明：指挥子网和设备子网的结构优化对整体网络性能的影响各异;相比传统的随机网络化方法,择优随机网络化方法的优化效能更高。  结论  后续研究可从改变子网之间的连接方式入手,解决末级指挥节点度过高的问题,以进一步改善损管指挥信息网络的综合性能。     

砰击载荷作用下船艏结构瞬态响应研究

  目的  为了提高砰击载荷对舰船疲劳损伤影响计算的准确性,提出一种计及砰击载荷的疲劳损伤直接计算法。  方法  首先,将非线性载荷的时域计算与线性频域的谱分析方法相结合,基于梁理论得到舰船短期海况下的应力时历;然后,采用雨流计数法和S-N曲线计算出考核点的损伤;其后,参考中国船级社（CCS）指南计算计及非线性砰击载荷对疲劳损伤的贡献度及影响系数,再结合谱分析方法修正对应的应力响应传递函数;最后,对应力谱进行计算,得到计及非线性砰击载荷的疲劳损伤。  结果  结果显示,相比传统谱分析方法,采用计及砰击载荷的舰船疲劳损伤直接计算方法得到的损伤结果其损伤度约增加了10%~50%。  结论  研究表明,对航行于恶劣海况下的舰船进行疲劳强度评估时,使用所提方法可以提高载荷计算的准确性。     

扁铲侧胀试验在黄土地区的应用

介绍扁铲侧胀试验的试验原理、资料整理以及参数计算方法,并初步与土工试验结果进行对比,结合扁铲侧胀试验在地铁勘察实际工程中的应用,说明该试验在黄土地区有较广阔的推广前景。     

加装箱形抗损结构的舰船主船体剩余强度分析

作战舰船必须具备承受反舰武器打击的能力。以GBU-12B／B激光制导炸弹直接命中船体主甲板为研究背景,比较分析舰船在遭受打击前后船体强度的变化,并提出在舰船主甲板下加装箱形抗损结构的方案。通过对甲板破口处进行有限元建模,计算该处的应力。分析箱形抗损结构对提高船体剩余强度的影响。研究结果表明,加装箱形抗损结构能够提高舰船剩余强度,进而提高舰船生命力。     

损伤引起加筋板结构屈曲性态变异研究

将损伤力学的相关原理引入到船舶常用加筋板结构的稳定性分析中,建立含损伤结构稳定的有限元分析模型。通过引入损伤位置、损伤程度和损伤面积三个独立的损伤参数来描述结构的受损状况,并分别分析它们的变化对结构临界屈曲载荷和屈曲模态产生的影响。对加筋板结构在各种载荷条件下的屈曲行为作了探讨,并通过对典型算例的数值模拟研究了不同损伤状况和不同屈曲模式下结构稳定特征的变异。     

基于改进的接触爆炸毁伤模型的航空母舰不沉性评估

针对传统航空母舰不沉性评估时采用指定破损舱组和校核规范无法对破损航空母舰生存能力给出定量评价的问题,首先建立基于单发和双发武器接触爆炸的毁伤模型来模拟舱段在武器毁伤中的破损,并在假定第1发毁伤参数固定的情况下,仿真计算破损航空母舰的浮态随第2发毁伤位置在全舰纵向和垂向变化的响应曲面,然后从满足校核规范和考虑海浪对破损航空母舰的不利影响两方面建立毁伤航空母舰的残存概率模型,可以对航空母舰在不同武器毁伤下的生存能力给出定量评价。该方法可以作为航空母舰方案设计阶段不沉性设计与评估的方法和手段。

     

水面舰船破损稳性的概率评估方法

水面舰船生命力的主要影响因素之一是舰船遭遇不同武器破坏下的薄弱性,而薄弱性主要由破损稳性决定。目前,舰船破损稳性评估主要运用确定性方法,但该方法不能全面评估舰船破损稳性。为了更加客观、全面地评估舰船破损稳性,探讨水面舰船破损稳性评估的概率方法,提出变区间线性插值计算残存概率S_i的新方法并开发计算程序。以某水面舰船为例,计算各种破损情况的进水概率P_i以及残存概率S_i,并累加所有破损情况P_i和S_i的乘积,得到分舱指数A。研究表明：通过将分舱指数A作为评估指标并考虑不同武器和碰撞的综合破坏效应,概率方法可以实现水面舰船破损稳性定量且整体的评估,能为舰船初步设计阶段主船体的分舱优化以致提高舰船生命力提供一种解决途径。