ABS轮速信号的采集方法研究

在分析现有轮速信号采集方法的基础上,提出了一种能够将精度和实时性相结合的速度测量方法--自适应的轮速信号采集方法.该方法可根据轮速大小采用变化的采样周期采集轮速信号.通过仿真和路试结果表明,该自适应轮速信号采集方法在全车速范围内均能满足采集精度与实时性要求.     

恩梯恩开发出车轮旋转传感器用高磁力橡胶制磁环

恩梯恩（NTN）开发出了用于ABS（防抱死系统）传感器的车轮旋转传感器用高磁力橡胶制磁环,可安装在车轮的轴承上使用。很多汽车的车轮轴承上均装有被称为ABS传感器的车轮旋转传感器,ABS传感器由磁性检测传感器和环状磁环构成。通过将磁环内置于车轮轴承中与轮胎一同旋转,并由磁性传感器感知此旋转引起的磁极变化,来对车轮的速度进行测量。     

发动机瞬时转速测量方法及试验研究

针对发动机瞬时转速的测量方法及测试系统进行了研究.分析了几种数字式瞬时转速测量方法的精度和分辨率,以及每转信号脉冲数与测量精度的关系,并指出现有瞬时转速测量方法的不足.在此基础上提出了瞬时转速测试分段优化方案,并设计了模拟试验系统.通过试验表明,所提出的测试方案及测试系统能够满足测试精度及实时性要求.     

基于驾驶员经验的自动泊车规划算法研究

为解决现有泊车算法中的原地转向和泊车实时性差与精度不足的问题,在借鉴熟练驾驶员泊车经验的基础上,对泊车过程的各个阶段进行机理分析,并建立相应的数学模型,设计了一种新的自动泊车规划算法。该算法包括泊车控制、转向控制和速度控制3个部分:泊车控制用于规划泊车路径,输出转向角和期望速度;转向控制用于控制转向盘反向转向的时机;速度控制用于控制车辆在泊车过程中的速度。仿真结果表明:所提出的算法能实现精确的自动泊车过程,既满足精度要求,又达到泊车控制的实时性要求。     

ABS齿圈节距误差与超差齿定位测试系统

建立了ABS齿圈节距数学方程,通过分析节距误差产生的原因,提出将齿圈节距测量转化为脉冲电信号进行测量的方法,并设计了ABS齿圈节距误差与超差齿定位的测试系统。介绍了测试系统的结构、数据采集及软件设计等,分析了不同测试参数对测试精度的影响。试验结果表明,该测试方法解决了机械与投影等方法无法对ABS齿圈进行准确测量的问题,利用该测试系统可准确得到ABS齿圈单齿误差与累计误差,同时可对超差齿位置进行定位。     

车辆加速度的测量装置及方法的研究

介绍了利用ADXL202双轴加速度传感器测量加速度和速度的装置,该装置以AT89C52单片机为核心,其串口 能够与计算机进行通信。它实现了对-1 g~ 1 g加速度和速度的实时测量显示,测量精度可达到8×10-3g。给出了系统 框图、关键电路图以及软件流程。     

分布式光纤传感技术在高速铁路测速中的应用

随着我国列车速度的不断提高,为保证行车安全,对列车的速度、距离监测变得越来越重要。当前的列车测速测距方式,其测量精度受到技术本身的限制。文中提出将分布式光纤传感技术应用于高速铁路测速测距,具有实时性好、灵敏度高、室外无源、监测距离长等优势,可准确提供列车行驶速度、方向、位置等信息。     

基于光电编码器的ABS检测系统误差分析

通过对ABS检测系统与光电编码器的结构分析,采用数学分析的方法对基于光电编码器的ABS检测系统的误差发生原因进行论证,总结出影响ABS检测结果的主要影响因素,为提高测量精度提供了理论依据。     

基于R树的非参数回归交通流预测方法

非参数回归在交通流预测中已得到广泛应用,但实际使用中存在实时性差的缺陷.为提高非参数回归预测速度,提出了使用空间索引结构R树作为模式库的存储结构,并依据R树空间聚类的特点进行K近邻搜索,最后根据搜索到的近邻点估算未来的交通流量.实验结果表明R树结构下的K近邻搜索速度比线性结构下的搜索速度提高了59.6%,但预测精度下降了8.8%.而通过缩小K近邻搜索中的距离上限这一参数,可以提高预测精度.结果表明当2种结构下的距离上限相同且小于0.02时,R树结构下的预测精度平均高于线性结构下11.9%,且搜索速度也平均提高了30.8%.因此,该算法能够在满足预测精度的条件下有效地提高预测速度,为实时短时交通流预测系统提供了1种实现算法.      

诊断ABS系统故障的技巧和方法

随着新型汽车特别是高级轿车在我国保有量的快速增加，汽车电子化程度呈现出越来越高的趋势，ABS系统是在制动时可防止车轮完全抱死且制动效果优于普通制动系统的刹车装置。它主要由电子控制器即ABS电脑、车轮速度传感器和执行器（即压力调节器）三部分组成。工作时，车轮速度传感器对车轮速度进行监测，并将信号传递给ABS电脑，ABS电脑接收车轮速度传感器传来的信号，经测量比较，放大分析，判别处理后，向压力调节器发出指令，调节器收到指令后对制动力进行调节，使制动性能处于最佳状态。     

高速道路入口匝道控制方法及应用探索

入口匝道控制是高速道路交通管理与控制的重要方法.对国外高速道路入口匝道的交通机理和控制方法进行系统分析和总结,重点对国外典型的多匝道动态协调控制算法进行论述,并对今后的研究方向提出展望.最后结合国内的实际情况,从交通量、几何线形、通道控制、协调配合、政策制定、仿真评价等方面对入口匝道控制在国内的相关工程应用做了初步探索.     

Gap metering for active traffic control at freeway merging sections

Freeway merging sections are critical segments that can recurrently activate peak-hour traffic congestion. This article proposes a novel vehicular gap control method as a new Active Traffic Management (ATM) strategy to be added to the existing Intelligent Transportation System (ITS) toolboxes for freeway merge control. The proposed strategy, “Gap Metering,” can be considered a non-stopping mainline version of ramp metering. It utilizes signals advising mainline through vehicles to yield sufficient gaps for merging vehicles. Detailed system design and control methods are proposed and implemented in VISSIM (please spell out the abbreviation of VISSIM for this first instance), a microsimulation software package. Different driver behavior sets with different standstill headway values are created to allow switching between gap-metered vehicles and regular vehicles. We evaluate the proposed system through two VISSIM models built and calibrated, respectively, for both the I-894 corridor in Milwaukee, WI, and the Riverside Drive segment on I-35 northbound in Austin, TX. Both corridors experience severe morning peak-hour congestion. We use the I-894 corridor for testing the system design parameters and use the I-35 corridor to conduct a comparison with the ramp metering strategies. The I-894 results indicate an average of 10–20% network delay reduction among all scenarios. We then tested the scenario on the I-35 corridor and compared with the ALINEAR ramp metering. Gap metering strategies alone or combined with ramp metering can, respectively, reduce 17% and 27% more total delay than ramp metering only control at 20% compliance rate.     

高速公路入口匝道控制算法用户公平性分析

入口匝道控制是高速公路交通控制有效策略之一。为避免早期的入口匝道控制算法往往只注重效率而忽视用户的公平性,从而造成入口匝道的排队增加的缺陷,将经济学中的Gini系数引入高速公路入口匝道控制算法分析评价中来反映用户的公平性,以出行时间节省比为效率指标,并以长春市绕城高速公路的净月立交入口匝道为例,通过实际数据调查及计算机模拟对假定实施的入口匝道控制各方案的公平性进行了分析,为高速公路入口匝道控制策略的选取提供依据。     

An exploratory investigation of the impact of ramp metering on driver acceleration behavior

Ramp metering has been proven as an effective freeway management strategy; however, the impact of ramp metering on drivers' acceleration behavior has not been fully investigated. A better understanding of acceleration behavior changes with ramp metering is critical to the adequate design of ramp metering facilities. In this study, drivers' speed and acceleration data were collected at two representative metered ramps in Los Angeles, California. The speed and acceleration profiles under meter-on and meter-off scenarios were compared. Statistical results demonstrated that ramp metering affects drivers' acceleration behavior at ramp acceleration lane. It was found that at the metered ramp with short existing acceleration length, the average acceleration rate from ramp meter stop bar to 500 ft downstream under meter-on scenario (4.72 ft./s²) is approximately 40% higher than when meter-off (3.18 ft./s²). The design of acceleration lane length for metered on-ramps should therefore take into account the potential impacts of ramp metering on driver acceleration behavior.     

Effect of fuel metering on combustion and emissions of a PFI gasoline engine during fast startup under an HEV-like mode

In this paper, the transient conditions during fast startup are investigated to develop a fuel metering strategy under HEV-like mode. The fuel mixture preparation and its effects on the combustion are analyzed in detail. Specifically, the combustion in the first cycle is characterized under both conventional low-speed cranking startup and HEV-like fast startup modes. The test results show that the enhancement of cranking speed has marginal effects on mixture preparation in the first cycle. However, it prolongs the combustion duration and reduces HC emissions. The sensitivity of the fuel metering is evaluated for the initial cycles. The combustion in the 3rd ~ 5th cycles during startup is found to be fairly sensitive to the fuel metering due to the effects of transient fuel film vaporization. The fuel metering in the first cycle has the most significant effect on the combustion and emissions during fast startup. Optimized fuel metering in the first cycle shows effective reduction of HC emissions during fast startup process.     

高压共轨系统高压泵进油计量阀仿真研究

根据高压共轨高压泵进油计量阀的结构,建立计量阀的比例电磁铁及液力阀的仿真计算模型,利用仿真分析方法,研究比例电磁铁的工作特性,比例电磁铁结构、材料等因素对比例电磁铁性能的影响以及不同形状节流孔液力阀的流通特性。结果表明:在理想工作气隙内,电磁吸力与激励电流成正比;在允许的设计范围内,比例电磁铁定铁端部的锥角越尖锐越有利于提升其电磁吸力的水平特性;比例电磁铁理想工作气隙的长度随定铁锥面的长度增大而增大,而电磁吸力随定铁锥面的长度增大而减小;在一定的衔铁长度内,比例电磁铁的电磁吸力随衔铁长度的增大而增大;三角形节流孔的计量阀比圆形和矩形的计量阀流量控制性好。研究的结果可以为高压共轨高压泵进油计量阀设计提供依据。     

A stochastic analysis of highway capacity: Empirical evidence and implications

This paper presents a stochastic characterization of highway capacity and explores its implications on ramp metering control at the corridor level. The stochastic variation of highway capacity is captured through a Space–Time Autoregressive Integrated Moving Average (STARIMA) model. It is identified following a Seasonal STARIMA model (0, 0, 2₃) × (0, 1, 0)₂, which indicates that the capacities of adjacent locations are spatially–temporally correlated. Hourly capacity patterns further verify the stochastic nature of highway capacity. The goal of this paper is to study (1) how to take advantage of the extra information, such as capacity variation, and (2) what benefits can be gained from stochastic capacity modeling. The implication of stochastic capacity is investigated through a ramp metering case study. A mean–standard deviation formulation of capacity is proposed to achieve the trade-off between traffic operation efficiency and robustness. Following that, a modified stochastic capacity-constraint ZONE ramp metering scheme embedded cell transmission model algorithm is introduced. The numerical experiment suggests that considering capacity variation information would alleviate the spillback effect and improve throughput. Monte Carlo simulation further supports this argument. This study helps verify and characterize the stochastic nature of capacity, validates the benefits of using capacity variation information, and thus enhances the necessity of implementing stochastic capacity in traffic operation.     

城市快速道路交通流建模和控制

首先回顾城市快速路宏观流体模型的发展，简析常用模型的推导建立过程，讨论宏观模型的使用。然后，以入口匝道流量调节作为受控快速路系统的控制输入，构造城市快速路交通流动态控制模型及最优控制问题，采用多层分散控制思想，给出一种实用的准最佳控制方法，通过交通仿真说明其有效性。     

基于数字化的工程量清单应用及优势分析

在工程项目中,工程量清单的编制是工程造价管理的基础工作。编制工作也需要投入大量的人力资源,仍然难以避免错、漏的问题,也无法进行有效的分类统计与精准管控,本质上是一堆表单。基于工程数字化的工程量清单编制模式,通过构建BIM模型,制定适用于清单编制和企业计量方式的编码规则库,搭建有效的数据库平台,提高编制效率的同时使得清单更精准、数据可追溯,并可延伸至成本分析、三算对比、原材料精准管控等多维度应用。提出的解决方案,在实际应用中收到较好的效果,具有较强的借鉴意义和推广应用价值。     

全速流动

流量测试表明，测量精度越来越高了。在原油价格很高的时候，在测量精度上即使是很小的改进都意味着大笔的钱。新技术使石油和天然气流量的测量精度更高且降低维护要求。因而能更好的对使用和消费进行监控。科氏力质量流量计是其中的一类，且正在对燃料行业的流量测量产生影响。6英寸和10英寸的Promass科氏力质量流量计已经通过了单向、双向和顺序校准。