地下车库联络道出入口设计研究

为保证地下车库联络道出入口设计能够满足运行安全的需求,弥补现行规范对地下车库联络道出入口线形指标和位置间距规定的空缺,调研国内已建和在建地下车库联络道现状,以郑东新区CBD副中心区地下道路和成都金融总部商务区地下道路为设计案例,对比市政和建筑行业规范中地下道路设计方面关键指标的差异,介绍地下车库联络道变速车道和渐变段长度的计算方法,建立地下车库联络道的运行速度协调性评价标准体系和计算模型。最后得出地下车库联络道线形设计的规范选择依据、地下车库联络道变速车道长度的取值标准、出入口位置的选择方法,并提出单向单洞地下车库联络道相邻出入口间距宜按1～3 min行程长度设置,以满足车行防灾疏散的要求。     

考虑合乘的共享自动驾驶汽车选择行为实证分析

共享自动驾驶汽车(Shared Autonomous Vehicles,SAV)是自动驾驶汽车和共享经济相结合的产物,为人们提供了一种新型的出行方式. 为探究出行者在考虑合乘的SAV与私家车或公共交通之间的选择偏好,实施了SAV选择意愿调查,并分析了考虑合乘的SAV的潜在用户特征. 基于问卷调查所得有效数据,采用K-Means 聚类法划分了历史出行模式,利用因子分析对性格态度特征进行了分类. 分别对有无私家车人群建立解释变量的参数服从不同分布的混合Logit 模型,并对参数标定结果进行对比分析. 研究结果表明,出行方式特性非常显著地影响出行者方式选择行为,性格态度特征是影响出行者选择考虑合乘的SAV出行方式的显著因素,且其显著性明显高于性别、年龄等社会经济属性.     

行程时间服从混合高斯分布的车队离散模型

为充分描述异质交通流条件下的车队离散规律,为信号配时优化、公交优先控制提供理论基础.考虑异质交通流条件下车辆行程时间分布特点,采用混合高斯分布拟合车辆行程时间分布.基于此,从流量角度推导了异质交通流条件下车队流量离散模型.通过实际调查数据,分析了下游交叉口到达流率分布与上游交叉口离去流率分布之间的关系,并将本文模型与Robertson模型、实际数据进行比较分析.结果表明,本文模型能够更好地描述异质交通流条件下的车队离散规律,与Robertson模型相比,平均预测均方误差减少了27%.     

彩色沥青路面的应用

介绍了彩色沥青路面的材料组成,同时也介绍了彩色沥青路面的优点和存在的缺陷,以及彩色沥青路面的应用现状,有利于提高人们对彩色沥青路面的认识。     

飞机起飞滑跑距离数值积分改进算法

应用数值计算理论对飞机起飞滑跑距离数值积分算法进行了研究,用插值法对发动机瞬时推力和起飞气动数据的确定方法进行了改进,用迭代法确定了离地速度,基于改进算法编制了起飞滑跑距离计算程序。在发动机推力曲线已知时,对5种飞机的起飞滑跑距离进行计算,原算法的平均误差为55.6 m,改进算法的平均误差为23.4 m;在发动机推力曲线未知时,用程序计算某型飞机在12种条件下的起飞滑跑距离与实际滑跑距离对比的平均相对误差为2.9%。计算结果表明改进算法计算精度优于原算法。     

基于混合壳单元法预应力混凝土T梁的受力性能

为了准确预测与评估预应力混凝土T梁的力学性能,利用混合壳单元建立了T梁有限元计算模型,对T梁从完好状态至破坏状态的力学行为进行了非线性分析。T梁中弯曲预应力钢筋采用组合壳单元模型,应用虚功原理推导了其对组合壳单元刚度矩阵的贡献,梁底平直预应力钢筋采用分层壳单元模型;利用Owen双参数屈服准则和Hinton压碎准则描述混凝土材料非线性特性,采用双折线本构模型模拟钢筋材料。分析结果表明:混合壳单元法计算结果与试验结果吻合良好,弹性阶段的T梁刚度折减不明显,非线性阶段刚度发生明显折减,跨中预应力钢筋应力增长幅度最大,因此,混合壳单元法对预应力混凝土T梁力学行为分析是有效的。     

Activity-based market equilibrium for capacitated multimodal transport systems

Empirical studies have shown that demand for multimodal transport systems is highly correlated with activity schedules of individuals. Nonetheless, existing analytical equilibrium models of multimodal systems have only considered trip-based demand. We propose a new market equilibrium model that is sensitive to traveler activity schedules and system capacities. The model is based on a constrained mixed logit model of activity schedule choice, where each schedule in the choice set is generated with a multimodal extension of the household activity pattern problem. The extension explicitly accounts for both passenger choices of activity participation and multimodal choices like public transit, walking, and vehicle parking. The market equilibrium is achieved with Lagrangian relaxation to determine the optimal dual price of the capacity constraint, and a method of successive averages with column generation finds an efficient choice set of activity schedules to assign flows over the dynamic network load capacities. An example illustrates the model and algorithm, effects similar to Vickrey’s morning commute model can be observed as a special case. A case study of the Oakville Go Transit station access “last mile” problem in the Greater Toronto Area is conducted with 166 survey samples reflecting 3680 individuals. Results suggest that a $10 fixed parking fee at Oakville station would lead to a reduction of access auto share from 54.8% to 49.5%, an increase in access transit share from 20.7% to 25.9%, and a disutility increase of 11% for the of single-activity residents of Oakville.     

SIV-DSS: Smart In-Vehicle Decision Support System for driving at signalized intersections with V2I communication

In this paper, we present a Smart In-Vehicle Decision Support System (SIV-DSS) to help making better stop/go decisions in the indecision zone as a vehicle is approaching a signalized intersection. Supported by the Vehicle-to-Infrastructure (V2I) communications, the system integrates and utilizes the information from both vehicle and intersection. The effective decision support models of SIV-DSS are realized with the probabilistic sequential decision making process with the capability of combining a variety of advantages gained from a set of decision rules, where each decision rule is responsible to specific situations for making right decisions even without complete information. The decision rules are either extracted from the existing parametric models of the indecision zone problem, or designed as novel ones based on physical models utilizing the integrated information containing the key inputs from vehicle motion, vehicle-driver characteristics, intersection geometry and topology, signal phase and timings, and the definitions of red-light running (RLR). In SIV-DSS, the generality is reached through physical models utilizing a large number of accurate physical parameters, and the heterogeneity is treated by including a few behavioral parameters in driver characteristics. The performance of SIV-DSS is evaluated with systematic simulation experiments. The results show that the system can not only ensure traffic safety by greatly reducing the RLR probability, but also improve mobility by significantly reducing unnecessary stops at the intersection. Finally, we briefly discuss some relevant aspects and implications for SIV-DSS in practical implementations.     

混合交通出行方式的瓶颈模型

运用瓶颈模型理论,在用户均衡条件下,对公共交通与私人交通并存的交通系统出行分布进行分析与扩展。分析公共交通的运行特点,考虑到公共交通存在的拥挤风险费用。而扩展包含了3个方面：一是在原有的交通系统上增加轨道交通这一交通方式;二是考虑公共交通与轨道交通运输能力的限制,运用拥挤风险费用进行分析;三是在考虑到私人小汽车与公共交通方式相互干扰的情况下,使模型更加符合实际。在用户平衡的前提下,通过计算出行者在选择三种交通方式成本的平衡点,得到不同情况下的需求分布。最后,给出一个简单的算例。     

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铁路集装箱中心站堆场作为集装箱列车装卸作业与集卡提交箱作业的缓冲区,堆存策略直接影响整个中心站的作业能力和效率,本文对铁路集装箱中心站堆场混堆优化问题进行了研究.根据中心站堆场混堆作业问题的描述,建立了两阶段优化模型,第一阶段平衡中心站堆场各箱区进口箱和出口箱的箱量,第二阶段为分配到箱区的集装箱指派较优箱位,使堆存所产生的压箱数最小,并设计了启发式算法对模型进行求解.最后利用某集装箱中心站的实际数据对模型和算法进行了验证,验证结果表明,该优化模型比中心站现有的堆存策略有较大改进.