分段线性变参数控制在数字式自动找平控制系统中的应用

为了验证分段线性变参数控制在自动找平控制系统中的应用前景,对自动找平控制系统的结构、控制方式进行了介绍;分析了分段线性控制方式的工作原理及特点,在实验室建立了沥青混凝土摊铺机数字式自动找平控制系统试验台,设计了3套试验方案,即普通电磁阀方案、高速开关阀方案和分段线性控制方案;对这3种控制方案进行了试验比较,得出了在阶跃干扰作用下,3种控制方案的响应速度及产生超调时的超调量。结果表明:分段线性控制方案具有较快的响应速度,但在系统产生超调时,其超调量相对较大。     

关于一、三级公路安全性认知因素的试验建模研究

在实测86处一级公路典型路段和188处三级公路典型路段道路结构基础上,确定驾驶员对国道一、三级公路的安全性认知因素集,进而针对一级公路的38处样本路段和三级公路的77处样本路段,组织47名驾驶人员进行现场认知评价试验,并应用模糊集合原理和模糊统计方法对评价试验得到的2829组(一级路673组、三级路2156组)有效认知试验评语数据进行分析处理,得到一、三级公路安全性认知因素的模糊评价隶属函数,从而给出驾驶人员对一、三级公路道路条件和交通环境的安全性模糊评价模型。     

水泥粉煤灰稳定碎石基层的龄期和强度

以水泥粉煤灰稳定碎石混合料的设计龄期和设计参数为研究对象,通过试验不同龄期的力学特性指标发现,120d龄期时混合料的强度发展已经基本完成,因此认定混合料的设计龄期宜为120d。在此基础上,通过变化集料级配和水泥剂量,研究确定出混合料7d龄期的抗压强度标准,120d龄期劈裂强度和抗压回弹模量的合理区间。     

钱江四桥抗震性能分析

根据钱江四桥地震危险性分析得到的地震动参数,基于两水准设防、两阶段设计的抗震设计思想,采用反应谱和时程分析两种方法对该桥的抗震性能进行了比较分析,分析时考虑了桩-土的相互作用及材料、伸缩缝、支座等非线形效应影响。研究结果表明:钱江四桥的抗震性能满足预期的设计性能目标,不会因地震而破坏。     

FSQ6125客车设计

简要介绍FSQ6125客车的设计目的、整车造型、主要结构特点和技术参数。     

新疆公路三级区划中环境参数的提出

自然环境条件对公路工程的影响，主要体现在路线选取、路基强度和稳定性、路面稳定性和耐久性、公路主要自然病害(包括冻融、翻浆、雪害、风沙害、崩塌、滑坡和地震灾害等)、施工条件和养护运营环境等5个方面，分析自然条件和公路工程的关系，提出公路区划中地质地貌环境参数和水热状况环境参数。阐述了环境参数的提出过程，为新疆公路自然区划三级区的划分提供依据。     

Predicting the adoption of connected autonomous vehicles: A new approach based on the theory of diffusion of innovations

On the grounds that individuals heavily rely on the information that they receive from their peers when evaluating adoption of a radical innovation, this paper proposes a new approach to forecast long-term adoption of connected autonomous vehicles (CAVs). The concept of resistance is employed to explain why individuals typically tend to defer the adoption of an innovation. We assume that there exists a social network among individuals through which they communicate based on certain frequencies. In addition, individuals can be subject to media advertisement based on certain frequencies. An individual’s perceptions are dynamic and change over time as the individual is exposed to advertisement and communicates with satisfied and dissatisfied adopters. We also explicitly allow willingness-to-pay (WTP) to change as a result of peer-to-peer communication. An individual decides to adopt when (i) there is a need for a new vehicles; (ii) his/her WTP is greater than CAV price; and (iii) his/her overall impression about CAVs reaches a cutoff value. Applicability of the proposed approach is shown using a survey of employees of the University of Memphis. Our results show that the automobile fleet will be near homogenous in about 2050 only if CAV prices decrease at an annual rate of 15% or 20%. We find that a 6-month pre-introduction marketing campaign may have no significant impact on adoption trend. Marketing is shown to ignite CAV diffusion but its effect is capped. CAV market share will be close to 100% only if all adopters are satisfied with their purchases; therefore, the probability that an individual becomes a satisfied adopter plays an important role in the trend of adoption. The effect of the latter probability is more pronounced as time goes by and is also more prominent when CAV price reduces at greater rates. Some caveats may be inserted when considering the study results as the findings are subject to sample bias and data limitations.     

Closed-form multiclass cell transmission model enhanced with overtaking,lane-changing,and first-in first-out properties

A novel multiclass macroscopic model is proposed in this article. In order to enhance first-in, first-out property (FIFO) and transmission function in the multiclass traffic modeling, a new multiclass cell transmission model with FIFO property (herein called FM-CTM) is extended from its prior multiclass cell transmission model (M-CTM). Also, to enhance its analytical compactness and resultant computational convenience, FM-CTM is formulated in this paper as a set of closed-form matrix equations. The objective is to improve the accuracy of traffic state estimation by enforcing FIFO property when a fast vehicle cannot overtake a slow vehicle due to a limitation of a single-lane road. Moreover, the proposed model takes into account a different priority for vehicles of each class to move forward through congested road conditions, and that makes the flow calculation independent from their free-flow speeds. Some hypothetical and real-world freeway networks with a constant or varying number of lanes are selected to verify FM-CTM by comparing with M-CTM and the conventional CTM. Observed densities of VISSIM and real-world dataset of I-80 are selected to compare with the simulated densities from the three CTMs. The numerical results show that FM-CTM outperforms the other two models by 15% of accuracy measures in most cases. Therefore, the proposed model is expected to be well applicable to the road network with a mixed traffic and varying number of lanes.     

桩基建模方法对自升式钻井平台动力响应的影响

随着海洋油气开采作业水深的不断增加,海洋平台固有频率随之降低,易与相同频率成分的波浪产生共振,因此对平台动力响应特性研究是非常有必要的,而桩基模型在平台动力响应分析中发挥着关键作用。以某400英尺自升式钻井平台研究对象,基于等效建模的思想,分别建立了固支桩基、铰接桩基、线性弹簧桩基及非线性弹簧桩基四种有限元模型,并对其进行静力分析、模态分析及瞬态动力学分析,通过对比得到的振动频率、动力放大因子及波流惯性力,得出弹簧桩基模型在平台动力响应分析中的有效性及合理性结论。     

Multi-criteria optimization of traffic signals: Mobility,safety, and environment

Two-dimensional multi-objective optimizations have been used for decades for the problems in traffic engineering although only few times so far in the optimization of signal timings. While the other engineering and science disciplines have utilized visualization of 3-dimensional Pareto fronts in the optimization studies, we have not seen many of those concepts applied to traffic signal optimization problems. To bridge the gap in the existing knowledge this study presents a methodology where 3-dimensional Pareto Fronts of signal timings, which are expressed through mobility, (surrogate) safety, and environmental factors, are optimized by use of an evolutionary algorithm. The study uses a segment of 5 signalized intersections in West Valley City, Utah, to test signal timings which provide a balance between mobility, safety and environment. In addition, a set of previous developed signal timing scenarios, including some of the Connected Vehicle technologies such as GLOSA, were conducted to evaluate the quality of the 3-dimensional Pareto front solutions. The results show success of 3-dimensinal Pareto fronts moving towards optimality. The resulting signal timing plans do not show large differences between themselves but all improve on the signal timings from the field, significantly. The commonly used optimization of standard single-objective functions shows robust solutions. The new set of Connected Vehicle technologies also shows promising benefits, especially in the area of reducing inter-vehicular friction. The resulting timing plans from two optimization sets (constrained and unconstrained) show that environmental and safe signal timings coincide but somewhat contradict mobility. Further research is needed to apply similar concepts on a variety of networks and traffic conditions before generalizing findings.