Does uncertainty make cost-benefit analyses pointless?

Cost-benefit analysis (CBA) is widely used in public decision making on infrastructure investments. However, the demand forecasts, cost estimates, benefit valuations and effect assessments that are conducted as part of CBAs are all subject to various degrees of uncertainty. The question is to what extent CBAs, given such uncertainties, are still useful as a way to prioritize between infrastructure investments, or put differently, how robust the policy conclusions of CBA are with respect to uncertainties. Using simulations based on real data on national infrastructure plans in Sweden and Norway, we study how investment selection and total realized benefits change when decisions are based on CBA assessments subject to several different types of uncertainty. Our results indicate that realized benefits and investment selection are surprisingly insensitive to all studied types of uncertainty, even for high levels of uncertainty. The two types of uncertainty that affect results the most are uncertainties about investment cost and transport demand. Provided that decisions are based on CBA outcomes, reducing uncertainty is still worthwhile, however, because of the huge sums at stake. Even moderate reductions of uncertainties about unit values, investment costs, future demand and project effects may increase the realized benefits infrastructure investment plans by tens or hundreds of million euros. We conclude that, despite the many types of uncertainties, CBA is able to fairly consistently separate the wheat from the chaff and hence contribute to substantially improved infrastructure decisions.     

Dynamics of connected vehicle systems with delayed acceleration feedback

In this paper, acceleration-based connected cruise control (CCC) is proposed to increase roadway traffic mobility. CCC is designed to be able to use acceleration signals received from multiple vehicles ahead through wireless vehicle-to-vehicle (V2V) communication. We consider various connectivity structures in heterogeneous platoons comprised of human-driven and CCC vehicles. We show that inserting a few CCC vehicles with appropriately designed gains and delays into the flow, one can stabilize otherwise string unstable vehicle platoons. Exploiting the flexibility of ad-hoc connectivity, CCC can be applied in a large variety of traffic scenarios. Moreover, using acceleration feedback in a selective manner, CCC provides robust performance and remains scalable for large systems of connected vehicles. Our conclusions are verified by simulations at the nonlinear level.     

青岛海湾大桥局部索构件失效对结构的影响及对策研究

以青岛海湾大桥航道桥为背景,采用半动力分析方法,研究分析了悬索桥吊杆及斜拉桥拉索失效后对周边结构的影响。结果表明：悬索桥吊杆的强健性较斜拉桥斜拉索好,单根或两根吊杆失效时不影响结构整体安全;而对于斜拉索,在两限或三根拉索失效时,结构可能因主梁应力的储备不足而破坏。根据分析结果,制定了结构损伤等级,给出了相应管理养护措施...     

基于QFT的四轮转向控制系统设计

本文提出一种基于定量反馈理论的主动控制四轮转向策略，以汽车转向时的横摆角速度和车体侧偏角为被控制量，将汽车的速度、质量、轮胎等效侧偏刚度等参数视为有界的不确定参数，应用定量反馈理论（QFT）设计反馈控制系统。为了验证设计的有效性，采用具有非线性轮胎特性的汽车模型对控制系统作了多种工况下的仿真。仿真结果证明所设计的解耦控制系统对汽车参数的不确定性具有鲁棒性，同时具有较好的控制特性，能够有效提高汽车的主动安全性和操纵稳定性。     

调整水资源开发中Conflict问题的分析研究

水资源开发的一个重要课题就是如何消除开发中存在的各方矛盾,正确认识、掌握参与对象（Players）的选好（preference）矢量是利用META-Game理论的扩张—Conflict数理解析法研究分析Conflict问题和确保获得真实均衡解的关键。文章首次利用集合论原理选好矢量,开发了3方以上META-Game的Robustness分析计算方法,并用长江三峡水资源开发项目对它的实用性进行了验证。     

基于反馈线性化的汽车AMT离合器滑模控制

电控离合器系统中，因为外界环境相当复杂，控制系统存在多种非线性，使得数学模型中参数是摄动的并且同时受到干扰，给机械式自动变速系统（AMT）的控制带来困难，针对离合器液压扫行机构，建立系统非线性动力学模型，进一步应用基于微分几何的反馈线性化方法，将原非线性系统等价为完全可控型线性化模型，然后设计滑模控制器，实车实验结果表明，设计的非线性控制器跟踪精度高，鲁棒性好。