统计能量法及其在提速客车噪声预测中的应用

为了预测提速客车内部噪声能量分布及噪声传递路径，用统计能量法对其进行了分析，讨论了统计能量法分析复杂振声系统的基本原理及稳态振声系统统计能量分析的基本方程．以唐山车辆厂提速客车为应用实例，获得了车内总的声功率在车底架、窗玻璃等主要传递路径上的能量分布，并给出了车窗双层玻璃不同厚度的高频响应以及车底架地板涂抹阻尼材料吸收低频声能的机理的治理措施。     

The effectiveness of a European speed limit versus an international bunker-levy to reduce CO2 emissions from container shipping

In the fight to reduce CO₂ emissions from international shipping, a bunker-levy is currently under consideration at the International Maritime Organization (IMO). Faced with the inability of the IMO to reach an agreement in the short term, the European Commission is now contemplating a unilateral measure of a speed limit for all ships entering European Union (EU) ports. This paper argues that this measure is counterproductive for two reasons. Firstly, because it may ultimately generate more emissions and incur a cost per ton of CO₂ which is more than society is willing to pay. Secondly, because it is sub-optimal compared to results obtained if an international bunker-levy was to be implemented. These elements are illustrated using two direct transatlantic services operated in 2010.     

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.     

Assessing the impact of reduced visibility on traffic crash risk using microscopic data and surrogate safety measures

Due to the difficulty of obtaining accurate real-time visibility and vehicle based traffic data at the same time, there are only few research studies that addressed the impact of reduced visibility on traffic crash risk. This research was conducted based on a new visibility detection system by mounting visibility sensor arrays combined with adaptive learning modules to provide more accurate visibility detections. The vehicle-based detector, Wavetronix SmartSensor HD, was installed at the same place to collect traffic data. Reduced visibility due to fog were selected and analyzed by comparing them with clear cases to identify the differences based on several surrogate measures of safety under different visibility classes. Moreover, vehicles were divided into different types and the vehicles in different lanes were compared in order to identify whether the impact of reduced visibility due to fog on traffic crash risk varies depending on vehicle types and lanes. Log-Inverse Gaussian regression modeling was then applied to explore the relationship between time to collision and visibility together with other traffic parameters. Based on the accurate visibility and traffic data collected by the new visibility and traffic detection system, it was concluded that reduced visibility would significantly increase the traffic crash risk especially rear-end crashes and the impact on crash risk was different for different vehicle types and for different lanes. The results would be helpful to understand the change in traffic crash risk and crash contributing factors under fog conditions. We suggest implementing the algorithms in real-time and augmenting it with ITS measures such as VSL and DMS to reduce crash risk.     

BRT速度影响因素分析及提高措施

本文分析了影响BRT速度的各个因素和计算方法,并提出提高BRT速度的改进措施,使在我国BRT规划实施前,全面掌握和了解影响速度的各个环节,以期能够在实际中顺利地达到快速的目的.     

低填方道路的路基处理

结合沈阳地区的工程实践,对低填方道路路基处理的目的、处理方法、处理措施评价等问题进行了探讨。     

济南市BRT速度运行及特征分析

“济南模式”BRT具有车辆双侧开门、中央岛式站台、同台免费换乘等特征,运营两年多来,对提高公交满意度、私人机动化交通方式转移、节能减排等方面发挥了一定效益。在分析济南BRT系统特征的基础上,客观评价了济南BRT速度运行情况。基于人工调查及行驶记录仪数据,解析BRT的行驶特征及时间-距离变化规律,从而分析延误的发生点、产生的原因及影响程度。速度的时间、空间分布特征分析结果表明,随着BRT的稳定运行,速度有所增长;工作日的速度具有明显的早、晚高峰现象,周末速度时变曲线则较平缓;空间上的路权保证是确保BRT高速运行的重要条件。速度运行评价及速度特性分析为近期改善策略及远期发展战略的制定提供一定依据。     

季节性冻土地区客运专线路基基床结构优化

对季节性冻土地区客运专线的路基基床结构进行了优化,通过现场填筑试验证实优化后的路基基床填筑方案,即铺设两布一膜,上覆5 cm中粗砂,再铺设55 cm厚级配碎石达到了检验标准,可在所研究的工程中推广使用。同时提出采用C25纤维混凝土代替原设计8 cm沥青混凝土作为防水层,优化后的防水层在施工操作性和质量保证方面有较大优势。     

高速铁路牵引计算层次约束方法

为了实现高速铁路牵引计算过程的连续性和自动化,研究并提出层次约束方法.根据高速列车具有连续控制能力的技术特点,给出以限速约束为主线、辅以操纵约束的层次约束方法计算步骤.按照当前限速段的出口速度必须满足下一限速段限速、当前限速段的入口状态应是前一限速段的出口状态的要求,通过建立入口状态反馈机制实现限速约束,解决了牵引计算的连续性问题;通过标准操纵曲线的运用实现了操纵约束,解决了牵引计算结果的实施性问题.以京沪高速铁路牵引计算为例验证了层次约束方法的实用性.     

新的改性沥青设备与加工技术

通过对沥青改性方法的研究 ,基于提高改性沥青单位小时产量的目的 ,探索出利用高速剪切和二次泵技术实施沥青改性。这种加工技术突破了以往沥青改性采用的“胶体磨”技术 ,适用范围广 ,可加工不同种类的改性沥青 ;采用该种加工技术提高了生产效率 ,产品的技术指标满足甚至超过规范要求。通过研制出的改性沥青生产设备制备出 PE、SBS、化学网构改性沥青等 ,而且将这几种改性沥青已应用于实体工程。