An Approach to Dynamic Classification of Traffic Flow Patterns

Abstract: Analyses on the dynamics of traffic flow, ranging from intersection flows to network‐wide flow propagation, require accurate information on time‐varying local traffic flows. To effectively determine the flow performance measures and consequently the congestion indicators of segmented road pieces, the ability to process such data in real time is out of the question. In this article, a dynamic approach to specify flow pattern variations is proposed mainly concentrating on the incorporation of neural network theory to provide real‐time mapping for traffic density simultaneously in conjunction with a macroscopic traffic flow model. To deal with the noise and the wide scatter of raw flow measures, a filtering is applied prior to modeling processes. Filtered data are dynamically and simultaneously input to processes of neural density mapping and traffic flow modeling. The classification of flow patterns over the fundamental diagram, which is dynamically plotted with the outputs of the flow modeling subprocess, is obtained by considering the density measure as a pattern indicator. Densities are mapped by selected neural approximation method for each simulation time step considering explicitly the flow conservation principle. Simultaneously, mapped densities are matched over the fundamental diagram to specify the current corresponding flow pattern. The approach is promising in capturing sudden changes on flow patterns and is open to be utilized within a series of intelligent management strategies including especially nonrecurrent congestion effect detection and control.     

基于建筑物交通流量分析的电梯交通配置方法

对建筑物的属性、建筑物所安装的电梯属性以及电梯运行模式进行了详细分析;提出了一种基于建筑物垂直交通流量分析的电梯交通配置软件编程思路。     

电梯交通流预测算法研究

高效电梯群控系统需要合理地安排与分配梯群对呼梯信号的响应,而准确的交通流量预测又是决定实时动态交通分配的重要因素,交通流量预测结果的好坏直接关系到交通控制与调度的效果。一种好的电梯群控系统交通流预测方法,能够为电梯群控调度算法的进一步研究提供依据,实现电梯的优化调度。     

城市路网交通流动态模型研究

从交通流的内在机理出发,通过对路网各交叉道口、路段目点和陷点的流量等参数的数量关系描述,导出用路段端口流量、速度、密度等参数表示的路段流量净增量方程组、路段间流量转移方程组、路网边界方程组以及路网总流量方程组等方程组群,全面描述路网各路段流量、速度、密度等交通参数的动态数量关系。只要路段端口流量、速度、密度连续可观,则可通过联立相关方程组,求出各路段产生的动态流量、邻接路段间流量动态转移系数以及路网动态总流量等动态参数,且边界方程的定义使路网可任意分割,有利于局部交通流动态分析。     

高速公路收费价格降低对客运车流短期流量影响的分析方法

分析高速公路收费价格降低后交通流量和交通组成的变化趋势,运用季节性多元时间序列模型确定价格对不同客运车辆的影响参数,对客运车辆进行价格需求弹性估计。所采用的客车弹性需求模型、影响参数以及不同车型价格弹性结论,可为高速公路管理者提供借鉴。     

Wavelet Packet-Autocorrelation Function Method for Traffic Flow Pattern Analysis

Abstract:   Accurate and timely forecasting of traffic flow is of paramount importance for effective management of traffic congestion in intelligent transportation systems. A detailed understanding of the properties of traffic flow is essential for building a reliable forecasting model. The discrete wavelet packet transform (DWPT) provides more coefficients than the conventional discrete wavelet transform (DWT), representing additional subtle details of a signal. In wavelet multiresolution analysis, an important decision is the selection of the decomposition level. In this research, the statistical autocorrelation function (ACF) is proposed for the selection of the decomposition level in wavelet multiresolution analysis of traffic flow time series. A hybrid wavelet packet-ACF method is proposed for analysis of traffic flow time series and determining its self-similar, singular, and fractal properties. A DWPT-based approach combined with a wavelet coefficients penalization scheme and soft thresholding is presented for denoising the traffic flow. The proposed methodology provides a powerful tool in removing the noise and identifying singularities in the traffic flow. The methods created in this research are of value in developing accurate traffic-forecasting models .     

既有建筑结构体系可靠性评估实用方法

回顾和总结了结构可靠度理论的发展历史以及既有建筑结构评估的研究现状,指出现有结构体系可靠性评估方法的不足.针对存在的问题,提出了基于子结构的既有建筑结构体系可靠性评估的简化方法,建议将子结构取为自然层,先对子结构进行可靠性评估,再根据子结构评定结果,通过结构自然层间的相关关系对结构体系可靠性进行评估.根据层次分析法,提出了一种适合工程应用的子结构中构件权重系数实用计算方法.工程实例分析结果表明,所提方法得出的评定结果能更好地符合实际情况.     

基于饱和交通量计算法的长寿命路面交通量预估

为了实现对长寿命路面交通量合理的预估,在常规交通量计算法的基础上,针对长寿命路面技术特征,对计算程序和计算方法进行了修改。在与常规方法相比较之后发现,饱和交通量计算法较好地实现了对长寿命路面交通量的预估。     

热电堆型热流计的一种标定方法

本文在简要分析热流计工作原理的基础上,利用双热流计式平板导热仪对自制的热电堆型热流计进行了标定,并对标定数据进行了线性拟合,分析了标定过程中可能出现的误差,为热流计在工程实际中的应用提供了依据.     

Calibration of Structural Models Using Fuzzy Mathematics

Abstract: A calibration model is presented that quantifies the uncertainties associated with structural free vibration analysis. System identification objectives and fuzzy set mathematics are integrated to formulate an analysis methodology that enables the a priori prediction of the most probable sources of modeling error. By first developing fundamental fuzzy sets defining uncertainty in structural parameters such as stiffness and design loading, higher-level fuzzy sets governing dynamic behavior are obtained using the vertex method. Uncertainty in the dynamic parameters (natural frequency, frequency ratio, and structural response) are each represented using fuzzy mathematics, where membership functions are determined by performing multiple dynamic analyses involving confidence levels of model assumptions. A numerical example is presented to demonstrate the calibration model for a 13-story steel structure located in San Jose, California. Results show that the calibration model is capable of quantifying uncertainties in structural properties and behavior without requiring the measured data necessary for conventional system identification procedures.     

无信号交叉口交通流有序运行实现方法研究

为改善无信号交叉口交通运行现状,基于自然排队思想,采用路中时间提醒装置使驾驶员获取无信号交叉口通行信息,对车速进行主动调整,达到自然排队的效果,在交叉口形成有序的交通流.运用不完全停车理论分析了此种方法对延误的降低,同时剖析了自然排队对交叉口交通的改善.实施方法的采取可以显著改善无信号交叉口的交通秩序,提高其通行能力.     

基于等效车流量的高速公路交通噪声预测模型

通过对美国联邦公路管理局（FHWA）公路噪声预测模型进行深入分析,引入等效车流量和等效车速概念处理混合车流,应用统计方法建立了高速公路中交通噪声自由传播的计算模型,并据此导出高速公路交通噪声预测模型。采用实测数据对模型进行了验证,结果表明,采用本方法建立的预测模型有效可行,且计算更加简便,预测结果比较符合我国高速公路交通现状。     

基于指数平滑技术的边坡位移预测方法

指数平滑技术是进行预测决策的有效方法，文章应用趋势型指数平滑模型预测了镇江市云台山滑坡区5号监测点的位移量。根据其观测值的数据特点(具线性趋势)，选取趋势型二次指数平滑的线性预测公式和相应的计算公式及合适的α值进行计算预测。预测结果表明，预测值与实际位移值之间的误差很小，说明此模型可很好地应用于斜坡变形位移的预测。     

基于“服务水平”概念的路网总体容量计算模型

引入"路网服务水平"概念,建立不同路网服务水平条件下的交通网络总体容量计算模型;根据交通流基本参数速度—流量—密度之间的基本关系,建立不同服务水平下各级道路的车流密度计算模型;进而确定道路交通网络系统所能承受的车辆数以及交通系统所能适应的交通需求总量,并结合青岛市城市综合交通规划,给出了路网容量计算实例.     

A Dantzig‐Wolfe Decomposition‐Based Heuristic for Off‐line Capacity Calibration of Dynamic Traffic Assignment

Abstract: One of the critical elements in considering any real‐time traffic management strategy requires assessing network traffic dynamics. Traffic is inherently dynamic, since it features congestion patterns that evolve over time and queues that form and dissipate over a planning horizon. Dynamic traffic assignment (DTA) is therefore gaining wider acceptance among agencies and practitioners as a more realistic representation of traffic phenomena than static traffic assignment. Though it is imperative to calibrate the DTA model such that it can accurately reproduce field observations and avoid erroneous flow predictions when evaluating traffic management strategies, DTA calibration is an onerous task due to the large number of variables that can be modified and the intensive computational resources required. To compliment other research on behavioral and trip table issues, this work focuses on DTA capacity calibration and presents an efficient Dantzig‐Wolfe decomposition‐based heuristic that decomposes the problem into a restricted master problem and a series of pricing problems. The restricted master problem is a capacity manipulation problem, which can be solved by a linear programming solver. The pricing problem is the user optimal DTA which can be optimally solved by an existing combinatorial algorithm. In addition, the proposed set of dual variable approximation techniques is one of a very limited number of approaches that can be used to estimate network‐wide dual information in facilitating algorithmic designs while maintaining scalability. Two networks of various sizes are empirically tested to demonstrate the efficiency and efficacy of the proposed heuristic. Based on the results, the proposed heuristic can calibrate the network capacity and match the counts within a 1% optimality gap.     

提升地下交通环廊利用效率的设计新思路

城市核心区的地下空间开发已经进入快速发展期,建设城市地下交通环廊是改善区域交通与环境的重要措施, 多应用于商务区、公共服务核心区等交通压力大、慢行环境品质要求较高的区域,是用于连接各地块地下车库并直接与城市道路相衔接。目前相关研究及规范对地下交通环廊功能定位、规划设计中应重点考虑因素的论证尚不成熟,且受政策、管理、规划设计、宣传等影响,已运营的地下交通环廊普遍存在运营效率不高等问题。本文重点从规划设计层面分析了环廊利用效率不高的原因,结合既有工程运营实践分析了既有设计规范的不合理点,并提出了规划设计新思路与新标准,并应用于西咸新区能源金贸区地下环廊规划设计实践,供行业实践及规范进一步修编参考。     

中心城区现代有轨电车交叉口的交通设计方法

以泉州市现代有轨电车项目为例,分析有轨电车在中心城区交叉口的主要节点。以交通影响分析和工程建设条件为基础,结合典型交叉口提出交叉口平面设计和下穿设计方法,并给出设计的关键要点。设计后具有良好的交通服务水平,能够兼顾有轨电车的运行效率和道路交通的通行需求,为现代有轨电车在中心城区的布设提供参考思路。     

天然气超声波流量计的应用及检定

介绍了天然气超声波流量计的工作原理和特点,探讨了干式检定和实流校准。     

建筑能耗模拟的校准方法

从计算质量控制的角度论述了国内外能耗模拟的差距,表明了模拟校准的重要性,并从气象参数、围护结构、作息、室内负荷和系统等5个方面阐述了建筑物能耗模拟的校准方法,最后总结了国外评价校准误差的标准。     

对我国城市混合交通问题的思考

剖析了我国城市机动车与非机动车混合交通的形成原因及混合交通所带来的交通问题,通过对道路交叉口和路网交通组织规律的分析,提出了构建机非路网分流体系的基本思路和今后研究的重点.