山区高速公路路面结构形式探讨

通过对我国山区高速公路路面情况的调查,结合国外山区高速公路路面现状,分析我国山区高速公路半刚性基层路面、组合式基层路面、柔性路面3种主要路面结构形式,并考虑到易发病害、成本、山区高速公路特点等因素,对半刚性基层路面、组合式基层路面、柔性路面3种主要路面结构形式提出相应优化建议。     

半刚性路面裂缝处理

半刚性路面普遍存在裂缝，雨水从裂缝进入路面结构层，导致路面严重破坏。美国CRAFCO路面密封胶能有效密封路面裂缝，达到密封路面裂缝的要求。     

复合式路面设计理念

随着公路交通运输业的发展,路面技术不断推上新台阶。文章结合复合式路面特点,分析了路面类型和路面应力,提出合理的复合式路面结构及路面设计的意见。     

高速公路路面施工存在的问题及预防措施

高速公路路面施工作为高速公路工程的重要组成部分,其组织管理和质量控制影响到高速公路路面质量。本文阐述了路面施工组织管理要点,提出了路面施工中可能遇到的质量问题以及从原材料选择、路面施工的动态管理、路面施工路面面层裂缝的防控和路面施工水破坏的防控等有效手段全方位把控路面施工的工程质量,以期为高速公路路面施工组织管理和质量控制提供借鉴。     

宣大高速公路水泥混凝土路面使用性能评价

结合宣大(宣化-大同)高速公路改建项目分析水泥混凝土路面使用性能评价原则、指标及方法。采用人工方法调查路面的损坏状况,车载式激光平整度仪测定路面平整度,摆式仪测定路面的摩擦系数,得出路面损坏状况指数PCI、路面行驶质量指数RQI、路面抗滑性能指数SRI,进而得到路面使用性能指数PQI;并采用落锤式弯沉仪测定路面弯沉值,得到路面结构强度指数PSSI。综合评定宣大高速公路现有路面使用性能,并提出相应的处治方案。     

基于FWD的水泥路面结构分析评价方法

弯沉是路面结构总体刚度的评价指标。路面承载力与路面弯沉不存在简单关系。通过弯沉盆检测数据反演路面结构材料性能，进行路面结构承载力与路面应力分析，进而对路面结构进行性能评价。     

基于FWD的水泥路面结构分析评价方法

弯沉是路面结构总体刚度的评价指标。路面承载力与路面弯沉不存在简单关系，通过弯沉盆检测数据反演路面结构材料性能，进行路面结构承载力与路面应力分析，进而对路面结构进行性能评价。     

人工神经网络在路面使用性能分析中的应用

沥青路面的使用性能包括：路面破损状况，路面结构强度，路面平整度和路面抗滑能力，其中路面破碎状况的检测比较困难，路面使用性能的4个指标之间是有内在联系的，但是它们之间的相互关系还没有研究清楚，如果用传统的数学方法分析，它们之间的相关系数较小，而对于用传统方法无法解决的问题，人工神经网络理论却能得到较好的结果，本文应用人工神经网络理论，分析路面使用性能之间的关系，得到利用路面结构强度，路面平整度和路面抗滑能力来预测路面破损的模型，从而减轻路面破损调查的工作量。     

基于虚拟试验场的强化路面建模方法研究

虚拟试验场是依据某汽车试验场建立的,可用于在仿真环境下对车辆进行路试试验。虚拟试验场的路面建模需要保证具有实际路面特性,文章针对虚拟试验场建立中强化路面的建立问题进行研究,提出一种方法,可以准确的建立虚拟试验场的强化路面。利用双轨路面计测量强化路面的不平度,对测试数据进行分析处理,保证测量结果的准确性,应用试验场规则路面的详细尺寸信息建立模拟路面。对于规则强化路面,应用实际尺寸和技术规范等信息建立,对于不规则强化路面,利用实际测量的路面不平度,通过功率谱估计、路面等级分析、路面不平度数字化等建立模拟路面。通过相关性分析,保证所建立的模拟路面的准确性和可信性。     

某试验场强化路三维虚拟路面重构与对比分析

对某试验场强化路面中线轨迹的测试数据,进行样条插值,还原路面轨迹,对测试的路面纵向5路高程数据,根据路面横向几何特征进行横向插值:横向几何特征一致的路面,采用线性插值;横向几何特征随机变化的路面,采用样条插值;横向几何特征不一致,但存在一定规律的路面,按其规律插值。最终依据相应的插值方法编程实现三维虚拟路面重构。进一步对重构的RDF和CRG格式路面进行对比的结果表明:CRG格式更适用于三维虚拟路面重构和动态载荷预测的动力学分析。路面特征越复杂,CRG路面在计算效率上相对RDF路面的优势更为突显。     

A vehicle type-based approach to model car following behaviors in simulation programs (case study: Car-motorcycle following behavior)

Traffic simulation models often neglect the important role of motorcycles and assume a flow of various combinations of cars. This paper addresses how much different would be the behavior of a car driver while following a motorcyclist compared to cases in which a car follows another car, along with a segment of an urban highway in the non-congested flow. Recognition of such a difference might help to develop existing simulation models and to improve the behavior of car drivers in such a way to lead to lower accidents with motorcycles. To reach the goal, a GHR (Gazis-Herman-Rothery) model for car following is applied and data have been collected by video cameras during 15?min time intervals in three different days. Analysis of 198 car-motorcycle and 374 car-car following observations has indicated that when a car driver follows a motorcycle, keeps a higher headway (about 10?m in the low speed) with a lower acceleration/deceleration in comparison with the situation in which car driver follow another one. It means that the behavior of the follower car driver would be more cautious compared to situations in which a car driver follows another one, especially in space headways <10?m. In addition to main findings of the paper for developing a more realistic simulation program, the paper also addresses that in cases when the required safe space between a car and a motorcycle would be endangered, a warning message could be generated for the car driver (by implementing an in-veh ITS technology) to warn driver about keeping a safe distance.     

Frequency Response Analysis of Canadian Logging Trucks

SUMMARY

This paper examines the frequency responses often logging truck configurations currently operating in the interior of British Columbia in Canada. The work is an extension of a previous study conducted at the National Research Council (NRC) in 1990. The previous study presented an extensive analysts of the directional responses and frequency responses of four Canadian log-hauling truck configurations; a tractor/pole trailer, a tractor/triaxle trailer, a tractor/quadaxle trailer (with a single load), and a tractor/single-axle-jeep/pole trailer. In the current study, the frequency responses of these four configurations are compared with those of six more log-hauling truck configurations; a tractor/ tandem-axle-jeep/pole trailer, a doglogger, a double doglogger, a tractor/quadaxle trailer (with a dual load), a tractor/jeep/triaxle trailer, and a tractor/jeep/quadaxle trailer. The current study makes use of three models developed by NRC in the previous study, and a new model developed at NRC in cooperation with the University of Victoria.

The frequency response method has been applied in this study to predict the lateral acceleration at the centre of gravity of each articulated vehicle unit, and the rearward amplification ratio. The logging truck simulation results have been compared with corresponding results, obtained using UMTRI's simplified models, for three conventional highway vehicles; a tractor/semitrailer, a B-train, and an A-train. The comparison provides a useful indication of the differences between the behaviours of logging trucks and conventional highway trucks in their shared environment.     

面向交通枢纽的车辆三维真实感实时仿真

为分析和解决城市交通拥挤问题并提高城市道路利用率提供可行的途径,提出了一种面向交通枢纽的车辆运行仿真方法,通过场景、道路与车辆的三维动态建模,实现交通枢纽交通状况的实时真实感仿真.首先,提出了基于道路关键点连接网络模型表示交通枢纽的通行道路.其次,基于粒子系统实现车辆的动态运行实时仿真,并采用基于空间剖分的车辆碰撞检测方法对车辆运动控制算法进行了优化.最终,通过对路段的动态观测和反馈机制实现车辆行驶路线的规划和调度.实验结果表明,本文提出的方法可以生动直观地呈现实际路面的交通状况,并且能以较为流畅的帧速率实现交通场景的动态仿真.     

考虑溶洞空间形态的路基岩溶顶板稳定性分析方法

岩溶路基随岩溶地区交通工程建设的快速发展而越来越普遍,如何评价岩溶路基稳定性成为岩溶区路基设计与施工的关键问题之一。针对目前路基岩溶顶板稳定性分析的不完善性,考虑溶洞形成过程中岩溶顶板所具有的空间形态特征,首先,将路基下伏岩溶顶板简化为固支梁、抛物线拱、圆拱与固支双向板等承载模型,以此进行路基岩溶顶板稳定性分析,并采用结构力学分析理论分别建立不同模型的路基岩溶顶板抗弯最小安全厚度计算方法;其次,通过典型案例的影响因素敏感性分析,揭示岩溶顶板最小安全厚度随溶洞顶板矢高、跨度、岩石抗拉强度与上覆荷载的变化规律,探讨路基岩溶顶板破坏模式的控制性因素及其影响规律,确定岩溶路基稳定性分析的基本原则;然后,基于岩溶地区地质勘察信息提出路基岩溶顶板稳定性分析过程,建立考虑溶洞空间形态特征的路基岩溶顶板稳定性分析方法;最后,通过工程实例计算分析验证所提方法确定的路基岩溶顶板稳定性评价结果的合理性与有效性。研究结果表明：岩溶顶板按何种模式破坏不仅与破坏形式有关,还与溶洞形态及其矢高密切相关,石灰岩抗拉强度同样影响较大,工程设计与稳定性评价时应基于勘测数据分析各种破坏模式,以便使设计或评价结果更接近实际情况。     

一种新型双动双腔真空增压器

EQ1060F轻型载货汽车的制动系统最初采用单腔制动总泵加单真空增压器及安全缸的半双管路结构。为了提高安全性，后采用双膜片真空助力器的双管路结构。为了适应使用要求，又改为两个真空增压器的方案，但仍存在结构复杂、接头环管多、易泄漏、自由行程过大，超载行驶时，感到制动力不足等问题。现采用一种新设计方案，以双腔制动总泵输出油压为控制源，用真空动力缸为增压机构，以双进、双出、双活塞的泵体为辅助缸，实现单真空增压器的双管路系统。     

A study on a dynamic model of a vehicle simulator with 6 DOF for the Korean tilting train

This article presents a dynamic model of a railway vehicle for the development of a 6-DOF (degrees of freedom) tilting-train simulator. It will be used to verify the tilting-electronics and tilting-control algorithm that are to be applied to the Korean tilting train. It is composed of 6 electrically driven actuators, a track generation system, a graphic user interface, and a visualization system with a 1600-mm-diameter dome screen. Each system shares the data by means of Ethernet network in real time. In this study, a train model of 9-DOF with a force generation system to tilt the train body has been used. Dynamic analysis for the straight track running and curve negotiation of a railway vehicle can be performed in the model. A verification study for the application of the model to the simulator has been conducted on curving tracks with different radii.     

Vehicle stability control using direct virtual sensors

The paper investigates the use of a direct virtual sensor (DVS) to replace a physical sensor in a vehicle stability control system. A yaw control system is considered and the proposed solution can be particularly useful when a fault of the yaw rate physical sensor occurs. A DVS is a stable linear filter derived directly from input–output data, collected in a preliminary experiment. In this work, it is shown that, by using data collected in a closed-loop fashion, better DVS accuracy can be obtained with a reduced number of measured variables. Moreover, the robust stability of the closed-loop system employing a DVS is studied. The effectiveness of the presented results is shown through numerical simulations of harsh manoeuvres, performed using a detailed model of a vehicle equipped with an active front steering device.     

Dynamic analysis of a pantograph-catenary system using absolute nodal coordinates

The dynamic interaction between the catenary and the pantographs of high-speed trains is a very important factor that affects the stable electric power supply. In order to design a reliable current collection system, a multibody simulation model can provide an efficient and economical method to analyze the dynamic behavior of the catenary and pantograph. In this article, a dynamic analysis method for a pantograph-catenary system for a high-speed train is presented, employing absolute nodal coordinates and rigid body reference coordinates. The highly flexible catenary is modeled using a nonlinear continuous beam element, which is based on an absolute nodal coordinate formulation. The pantograph is modeled as a rigid multibody system. The analysis results are compared with experimental data obtained from a running high-speed train. In addition, using a derived system equation of motion, the calculation method for the dynamic stress in the catenary conductor is presented. This study may have significance in providing an example that a structural and multibody dynamics model can be unified into one numerical system.     

2011上半年重卡市场分析及下半年展望

2011上半年,我国商用车产销同比分别下降6.07%和3.67%,除客车产销同比增长外,其余均低于上年同期,半挂牵引车降幅最为明显。我国汽车产销在持续了2年的高速增长后,由于国家宏观经济政策的调整、购置税优惠等有关利好政策的退出以及自身调整的影响,上半年增速大幅回落,由上年的高速增长转为平缓增长,且呈现逐月回落的走势。     

Wave Propagation in a Finite Cascade of Masses and Springs Representing a Train

The response of a train, modelled with a cascade of bodies and springs, due to a step force at the locomotive is investigated. In this model the mass of the locomotive and the last wagon may differ from that of the other wagons. An analytic solution is given for a finite and for a semi-infinite cascade and a comparison to the solution of a continuous model is made.