郊区自驾游旅游交通指引标志设置研究

当前旅游交通指引标志设置中存在缺乏区域系统考虑、设置分散、旅游信息过于集中等问题,导致自驾游出行者难以及时、准确、连续地获得指引信息。针对这一问题,从郊区自驾游出行者的需求出发,构建区域入口、区域内部、景区附近的旅游交通三级指引系统。重点探讨二级指引标志的设计原则与方法,提出在景区重要度分类和道路节点重要度分级的基础上,确定各景区指引范围和各道路节点指引容量,对旅游交通指引标志进行选址。最后以河北省平山县为例,对提出的旅游交通指引标志设置方法进行实证研究。     

北京市老年人出行调查与分析

在当今人口老龄化背景下,为了解老年人的生活及出行状况、提高老年人的生活质量,对北京市60岁以上部分老年人进行出行调查。调查包括一日出行情况、个人家庭基本属性、主要日常活动、出行意愿四项内容。通过调查分析得出北京市老年人的总体出行特征和不同属性的老年人出行特征,老年人主要日常活动的活动频率、空间分布、时间分布特征及主要出行方式,日常出行所面临的困难及改进老年人出行环境应关注的事项。     

突加负载时感应电动机动态过程的仿真

首先利用三相感应电动机的运动方程,推导出它的状态方程,并结合实际电机参数利用MATLAB语言对空载运行的三相感应电动机突加负载时的动态过程进行了仿真。仿真结果符合三相感应电机的动态过程的特性。     

耦合非线性三维海洋立管的边界控制(英文)

This paper presents a design of boundary controllers implemented at the top end for global stabilization of a marine riser in a three dimensional space under environmental loadings. Based on the energy approach, nonlinear partial differential equations of motion, including bending-bending and longitudinal-bending couplings for the risers are derived. The couplings cause mutual effects between the three independent directions in the riser’s motions, and make it difficult to minimize its vibrations. The Lyapunov direct method is employed to design the boundary controller. It is shown that the proposed boundary controllers can effectively reduce the riser’s vibration. Stability analysis of the closed-loop system is performed using the Lyapunov direct method. Numerical simulations illustrate the results.     

基于活动的旅游出行链选择行为研究

通过对在京旅游的游客进行调查,以游客的个人属性和出游属性作为影响因素,将游客对不同类型活动的时间分配作为前提,对游客的出行链选择行为建立了Multinomial Logit模型。模型分析表明:年龄、职业、出游时间、是否本地游客、对景点是否熟悉以及游客对活动时间的分配等均对出行链选择有显著影响;模型具有较高的精度,为游客出行预测提供了理论依据。     

悬架K&C特性在底盘性能分析中的研究

归纳出影响车辆转向特性的各种因素,并用悬架K&C参数定量化;提出车辆在常用车速直线行驶时期其前束角和外倾角应尽量为零,以保证轮胎磨损尽量小,并建立了行驶时前束角及外倾角的表达式;将各向力作用下的变形统一为悬架及轮胎刚度,并分析了各种刚度的意义;通过悬架K&C特性计算出动力学参数,建立了研究操纵稳定性及底盘电控的虚拟车辆,并在Carsim和ADAMS软件中实现.     

基于凯恩方法的汽车悬架实时仿真模型

提出了一种用于汽车动力学实时仿真的悬架建模方法。将悬架系统模型建成为连接车身和车轮的无质量复合铰,并基于凯恩方法推导了悬架复合铰的运动方程。在满足动力学实时仿真要求的同时不降低悬架系统的运动学精度。利用该方法建立了某轿车面向结构的麦弗逊式前悬架模型,并集成到由符号计算软件产生的该轿车的多体动力学模型中。仿真与实车道路试验结果的对比表明该悬架模型具有较高的仿真精度。     

基于虚拟技术的汽车组合仪表测试系统设计

针对汽车组合仪表测试问题,以NI公司LabVIEW软件为基础,硬件采用NI公司的USB-6008数据采集卡,进行基于虚拟技术的汽车组合仪表测试系统的设计。结果表明该测试系统具有设计周期短、成本较低、便携性、易扩展性和操作直观的优点。     

基于非集计模型的居民出行方式选择行为研究

基于ML模型的基本理论与建模方法,利用2009年济南市居民出行调查数据,对影响城市居民出行方式选择的因素进行了分析,确定了影响居民出行方式选择的特性变量,建立了居民出行方式选择ML模型.研究结果表明:居民出行方式选择与个人属性、家庭属性和出行属性之间有较稳定的关系,通过对影响居民出行方式选择的可控影响因素进行引导和调整,可以达到优化和调整交通方式结构的目的.     

Effect of various LPG supply systems on exhaust particle emission in spark-ignited combustion engine

The particle size distribution and particle number (PN) concentration emitted by internal combustion engine are a subject of significant environmental concern because of their adverse health effects and environmental impact. This subject has recently attracted the attention of the Particle Measurement Programme (PMP). In 2007, the UN-ECE GRPE PMP proposed a new method to measure particle emissions in the diluted exhaust of automotive engines and a regulation limit (<6.0×10¹¹ #/km, number of particles). The specific PN regulation of spark-ignited combustion engine will be regulated starting on September 1, 2014 (EURO 6). In this study, three types of LPG supply systems (a mixer system and a multi-point injection system with gas-phase or liquid-phase LPG fuel) were used for a comparison of the particulate emission characteristics, including the nano-sized particle number density. Each of the three LPG vehicles with various LPG injection systems contained a multi-cylinder engine with same displacement volumes of 2,000 cm³ and a three-way catalytic converter. The test fuel that was used in this study for the spark-ignited combustion engine was n-butane basis LPG fuel, which is primarily used for taxi vehicles in Korea. The characteristics of nano-particle size distribution and number concentration of particle sizes ranging from 20 to 1,000 nm (aerodynamic diameter) that were emitted from the three LPG vehicles with various LPG supply systems were investigated by using a condensation particle counter (CPC), which is recommended by the PMP under both the NEDC and FTP-75 test modes on a chassis dynamometer. The experimental results indicate that the PN emission characteristics that were obtained by the CPC system using the PMP procedure are sufficiently reliable compared to other regulated emissions. Additionally, the sources of PN emissions in ascending order of magnitude are as follows: mixer type, gas-phase LPG injection (LPGi) and liquid-phase LPG injection (LPLi) passenger vehicles. The liquid-phase LPG injection system produced relatively large particle sizes and number concentrations compared to the gaseous system, regardless of the vehicle driving cycle. This phenomenon can be explained by unburned micro-fuel droplets that were generated due to a relatively short homogeneous fuel-air mixture duration in the engine intake manifold. Also the particle number emissions from the LPG vehicle were influenced by the vehicle driving cycle.