宝马iX3驱动系统新技术剖析(三)

7.售后服务信息如果在维修过程中打开了冷却液循环回路,则接下来必须对其进行加注和排气。冷却液循环回路的加注必须使用真空加注机进行。除此以外,在加注前,必须从冷却系统中抽取最少3L的冷却液。这样做的目的是让真空加注机能够产生相应的负压,并且不会抽吸冷却液。     

浅谈环境影响评价中的公众参与

我国相关环境保护法律规定:任何建设项目在兴建之前,都必须进行环境影响评价工作。而且在环境影响评价技术导则中又明确规定了在进行建设项目环境影响评价工作中,必须有公众参与。自从《环境影响评价公众参与暂行办法》实施以来,环评单位规范了公众参与的形式和内容。     

公路隧道的施工特点和监理方法浅析

分析了隧道施工的特点及其对施工监理人员的要求,指出监理人员在隧道施工中必须检查的重点工程。同时指出,监理工作必须要了解"新奥法"原理并能在施工中灵活运用,并且要重视有实践经验的施工队伍的建议。     

电力配电工程中电缆敷设技术的运用刍议

在配电业务中,必须不断扩大电力电缆的使用范围,并且必须对电力电缆线路进行严格的检查,以确保可靠地发电。在城市发展过程中,由于电缆的大规模应用,出现了许多施工问题。基于此,本文将从五个方面分析电力配电工程中电缆敷设技术的运用策略,以此来供相关人士交流参考。     

预应力张拉计算及现场张拉控制

针对预应力砼张拉施工过程中必须控制的张拉应力和伸长值提出了具体的计算方法,说明了预应力张拉施工必须严格执行JTJ041-2000《公路桥涵施工技术规范》要求的"双控"标准,确保预应力张拉的质量。     

广佛高速公路扩建工程的排水

广州-佛山高速公路扩建工程是国内首例高速公路扩建工程。高速公路扩建中排水系统的设计不但要遵循新建公路排水系统的设计原则，而且必须注意与原有排水设施的顺利衔接，因此在设计前必须对原有排水设施进行认真细致的调查。介绍了广佛高速公路扩建工程中排水系统的设计。     

和谐文化 成就价值——李海平再谈中通企业文化

经历了波澜壮阔的改革开放三十年,中国正在进入伟大的民族复兴时期。我们的国家要屹立于世界民族之林,就必须有足够的经济实力,必须有一大批国际一流的企业。中通客车的抱负就是要做这样的企业,以振兴发展民族经济为已任,肩负起民族的希望和时代的使命。中通客车何以能承担起这种使命呢？     

郑州市城市高架路设计中的景观分析

景观设计是城市高架路设计中必须重视的课题。该文结合郑州市的地域文化特征,本着以人为本的理念,从各个细节对以往郑州市城市高架路的景观设计进行了分析,指出了今后郑州市高架路景观设计中应该注意的问题。     

重视标准 贯彻标准

在国家《标准化法》、《质量法》、《道路交通安全法》、《工业产品生产许可证管理条例》和《助力车产品许可证换(发)证实施细则》等法律、法规中,都十分明确地规定了产品的生产和销售必须符合国家现有的标准。因此,自行车生产企业必须在法律、法规     

高等级公路机械化施工的实践

近几年来,我们考虑到公路改建工程必须机械化的形势,在筑路机械的购置、使用及管理上摸索了一定的经验,取得了较好的经济效益和社会效益。特别是在207国道荆门南段二级公路的技术改造工程中,多渠道积累资金,购置了一定数量的机械设备,充分发挥机械使用效率,为高速、优质完成改建工程起到了决定性的作用,坚定了公路建设必须机械化的信心。1 认真对比算帐,转变传统观念荆门是一个新兴的工业城市,交通流量日益增长,公路运输任务越来越重,原有公路等级和承载能力已不相适应。必须加快公路建设速度,提高公路等级,迅速改变各种落后状况。改建工程如果单靠传统的手工作业,质量和速度难以保障,必须实现机械化     

Evaluation of idle stability through in-situ torque measurement in automatic transmission vehicles

Idle stability directly affects a vehicle’s NVH (Noise, Vibration and Harshness) and is closely related to driver satisfaction. The present study proposes a method of measuring an engine’s idle roughness, which is useful in quantifying the idle stability. Engine brake torque was measured directly using a torque sensor, which can be installed without modification of the engine’s mounting structure. In addition, angular acceleration was measured at the same position as the torque measurement, to compare dynamic characteristics of the angular acceleration with the torque variation. Both torque and angular acceleration oscillate between positive and negative values. In this study, torque data were divided into several regions, and each region starts from the point where the torque data changes its sign from negative to positive. The root mean square values of both torque and angular acceleration were calculated for each region. This calculation showed a very good correlation between the torques and the angular accelerations. The idle stability was evaluated with the standard deviation of the measured torque, and the cycle-to-cycle variation is a more dominant factor in the idle stability than is the cylinder-to-cylinder variation. Because it is easier to measure the angular acceleration than to measure the torque, the variations of angular accelerations are usually compared between engines. However, the present study showed that the moment of inertia of an engine and the angular acceleration should be considered together when comparing the idle stability between engines.     

基于传声器阵列的摩托车噪声源分析

现有的摩托车噪声源分析主要是基于近场声压测量法和声强测量法等;然而,这些方法获取的信息十分有限,而且测试相当耗时。采用最大加速行驶噪声工况基准法模拟摩托车最恶劣噪声场,并应用一种不规则形状的传声器阵列对摩托车噪声源进行试验分析,从而获得匹配的声强（或声压）分布图。通过声场分布图,可直观得到各主要噪声源的分布、强度和频率,并可方便制定出合理的摩托车降噪技术方案。试验结果表明,最大加速行驶噪声工况基准法能准确模拟摩托车最恶劣噪声场,基于传声器阵列的噪声源分析路线和方法准确有效,这：恃有助于改善摩托车噪声。     

在用汽油车ASM方法测量结果影响因素研究

分析对比了双怠速法和ASM方法测量在用汽油车排气污染物的优缺点,特别研究了影响ASM方法测量结果的主要因素和提高测量结果准确度的主要措施,并给出了几种测量方法的测量结果对比。     

基于离散-连续耦合的落锤-路面动态相互作用研究

落锤冲击是一种典型的中低速碰撞，也是现今工程技术中的重要力学问题。在公路工程领域，一方面利用落锤产生的巨大瞬时冲击力达到压实、加固、微裂、破碎、检测等目的，另一方面是避免过大的冲击力对结构物产生破坏作用。为了探索落锤-路面动态相互作用规律，基于PFC5.0 Suite和FLAC3D构建了离散-连续耦合模型，模拟无损和有损状态下水泥路面板承受落锤冲击过程中加速度的变化规律。通过路面无损状态下的仿真结果分析发现：①落锤冲击加速度曲线拥有多个波峰和波谷，且均与路面和落锤参数具有相关性；②冲击加速度峰值与落锤高度和水泥板模量正相关，而与落锤质量负相关；③落锤高度对冲击持续时间影响不大，而落锤质量将显著增长冲击持续时间。通过路面有损状态下的仿真结果分析，发现：①冲击加速度曲线特征点与路面破损状态密切相关；②随着水泥面板破损程度增大，冲击加速度值整体减小，冲击持续时间延长；③落锤高度和质量对路面破损模式的影响差异较大，前者主要引起表面破损，而后者主要引起底部破损。研究认为：落锤冲击加速度特征值与路面破损程度和破损模式之间存在密切的关联，相关研究结果可用于路面破损检测、破碎或微裂状态评价等实际工程中，同时也可为工程器械的改进和研发提供基础支撑。     

金凤隧道监控量测技术及数据分析

以金凤隧道为例介绍了隧道监控量测的目的和意义、内容和方法,并对监测数据进行了分析。结果表明隧道在开挖期间围岩周边收敛、拱顶沉降、钢支撑内力、围岩位移等监测指标随时间的变化规律基本一致,都经历了加速、稳定、再次加速、最终稳定四个阶段,稳定值均在规范要求的范围内,说明隧道初期支护合理,可安全进行二衬施工。     

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.     

山区道路橡胶减速带车辆运行特性分析

为明确山区道路中减速带布设对车辆运行的影响，选择在重庆市主城区江南立交开展减速带布设区域的实车试验，采集了车辆的速度和加速度等数据，以此分析试验路段的运行特征。结果表明:①速度分布带宽在减速带两侧各40 m左右达到极小值，在减速带位置速度带宽出现反弹，表明在减速带布设位置车辆运行速度差异较大，容易产生追尾风险；②减速带对驾驶员的速度选择行为有较强的约束力，且2个减速带相隔越近对速度选择行为的约束作用越强，减速效果更好；③通过减速带之前的初速度越大，所需的减速长度越长，应越早采取减速措施；85th百分位减速长度值和加速长度值分别为225，212 m；④车辆通过减速带时的加速度、减速度与制动初速度、加速前初速度的大小密切相关；道路环境越复杂，车辆通过减速带时减速度与加速度曲线的差异性越显著；⑤减速带对车辆的速度折减率上限可达0.9，下限随初始速度的增大而增加。      

Perspectives on railway track geometry condition monitoring from in-service railway vehicles

This paper presents a view of the current state of monitoring track geometry condition from in-service vehicles. It considers technology used to provide condition monitoring; some issues of processing and the determination of location; how things have evolved over the past decade; and what is being, or could/should be done in future research. Monitoring railway track geometry from an in-service vehicle is an attractive proposition that has become a reality in the past decade. However, this is only the beginning. Seeing the same track over and over again provides an opportunity for observing track geometry degradation that can potentially be used to inform maintenance decisions. Furthermore, it is possible to extend the use of track condition information to identify if maintenance is effective, and to monitor the degradation of individual faults such as dipped joints. There are full unattended track geometry measurement systems running on in-service vehicles in the UK and elsewhere around the world, feeding their geometry measurements into large databases. These data can be retrieved, but little is currently done with the data other than the generation of reports of track geometry that exceeds predefined thresholds. There are examples of simpler systems that measure some track geometry parameters more or less directly and accurately, but forego parameters such as gauge. Additionally, there are experimental systems that use mathematics and models to infer track geometry using data from sensors placed on an in-service vehicle. Finally, there are systems that do not claim to measure track geometry, but monitor some other quantity such as ride quality or bogie acceleration to infer poor track geometry without explicitly measuring it.