横荡对被动式减摇水舱运动的影响研究

被动式减摇水舱是减少船舶摇摆的重要装置之一,目前对它的研究大多数都只针对单纯横摇运动。而本文在考虑了横荡对水舱运动的影响后,基于U型被动式减摇水舱理论推导了耦合横荡的“船舶一水舱”系统的数学模型,并通过仿真和试验研究证实了考虑横荡对水舱的影响是很必要的,更符合于实际情况。     

浅谈粉煤灰在水泥稳定砂砾底基层中的应用

介绍了粉煤灰在水稳底基层施工中的应用,阐述了施工配比、施工工艺及相关注意事项,提出适量降低水泥用量及增加粉煤灰对水稳砂砾底基层的积极作用,是防治底基层开裂的重要方法。     

基于台架检测汽车滚动阻力的修正模型

通过研究底盘测功机台架与实际道路的滚动阻力之间存在的差异.以及对车轮在台架上滚动阻力的分析,建立了车辆台架检测滚动阻力修正模型.以某型汽车为例,对该模型进行了台架对比试验验证.利用该模型求得检测车辆在任意滚筒直径的底盘测功机上的加载功率,其精度满足测功机检测规程中的规定.     

超越离合器的力学分析

全面分析了内星轮滚柱式超越离合器工作时４个阶段的力学特点,并对各主要影响因素进行了讨论。指出,滚子惯性、滚动摩擦系数以及压紧弹簧力学对离合器的性能有重要作用,在分析中不能忽略。     

Closing the loop in real-time railway control: Framework design and impacts on operations

Railway traffic is heavily affected by disturbances and/or disruptions, which are often cause of delays and low performance of train services. The impact and the propagation of such delays can be mitigated by relying on automatic tools for rescheduling traffic in real-time. These tools predict future track conflict based on current train information and provide suitable control measures (e.g. reordering, retiming and/or rerouting) by using advanced mathematical models. A growing literature is available on these tools, but their effects on real operations are blurry and not yet well known, due to the very scarce implementation of such systems in practice.In this paper we widen the knowledge on how automatic real-time rescheduling tools can influence train performance when interfaced with railway operations. To this purpose we build up a novel traffic control framework that couples the state-of-the art automatic rescheduling tool ROMA, with the realistic railway traffic simulation environment EGTRAIN, used as a surrogate of the real field. At regular times ROMA is fed with current traffic information measured from the field (i.e. EGTRAIN) in order to predict possible conflicts and compute (sub) optimal control measures that minimize the max consecutive delay on the network. We test the impact of the traffic control framework based on different types of interaction (i.e. open loop, multiple open loop, closed loop) between the rescheduling tool and the simulation environment as well as different combinations of parameter values (such as the rescheduling interval and prediction horizon). The influence of different traffic prediction models (assuming e.g. aggressive versus conservative driving behaviour) is also investigated together with the effects on traffic due to control delays of the dispatcher in implementing the control measures computed by the rescheduling tool.Results obtained for the Dutch railway corridor Utrecht–Den Bosch show that a closed loop interaction outperforms both the multiple open loop and the open loop approaches, especially with large control delays and limited information on train entrance delays and dwell times. A slow rescheduling frequency and a large prediction horizon improve the quality of the control measure. A limited control delay and a conservative prediction of train speed help filtering out uncertain traffic dynamics thereby increasing the effectiveness of the implemented measures.     

The importance of the use phase on the LCA of environmentally friendly solutions for asphalt road pavements

In order to assess sustainability of products and processes, different methodologies have been developed and used in the last years. In the road pavement construction area, most methodologies used for Life Cycle Assessment (LCA) are essentially focused in the construction phase. The present paper analyses the importance of the use phase of a road in the LCA of different paving alternatives, namely by evaluating energy consumption and gaseous emissions throughout the road pavement’s life. Therefore, a new LCA methodology for road pavements was developed, and the results of its application to a case study involving the construction of alternative pavement structures are discussed. The study intends to assess the influence of using more sustainable paving construction alternatives (asphalt recycling vs. conventional asphalt mixtures), and/or different surface course materials (which have a higher influence on the rolling resistance and, therefore, affect the performance during the use phase). The LCA results obtained for this case study showed that the reductions in energy consumption and gaseous emissions obtained during the use phase, for pavement alternatives with a lower rolling resistance surface course, are higher than the total amount of energy consumption and gas emissions produced during construction. It is therefore clear that some improvements in the characteristics of the surface course may have an effect over the road use phase that will rapidly balance the initial costs and gas emissions of those interventions. The LCA results obtained also showed that the sustainability of pavement construction may also be improved using recycled asphalt mixtures.     

An analysis of the methods used to calculate the emissions of rolling stock in the UK

The aim of this paper is to analyse and compare the methods used for calculating emissions of UK rolling stock based on their type and mode of operation. The three modes under comparison were; diesel, electric and bi-mode. As well as comparing these three modes of operation, a comparison between Conventional, Freight and High Speed Rail was made. Alternate fuels were considered for diesel and bi-mode locomotives and compared based on their environmental impact. The emissions of trains were studied using three methods. Specifically, the three chosen methods were used to calculate the emissions of each train and a comparison of these methods was made. In the current UK energy climate, diesel trains emit less emissions than electric trains when factoring in mechanical and air resistances. Bi-mode trains have their place in the UK network but with electrification of the network currently in place, this mode of operation will become redundant in the near future. High Speed Rail, although time efficient, releases high emissions due to energy consumption increasing with the square of speed. Alternative fuels, such as biodiesel, should be a consideration for the future of rail, as emissions fall dramatically with content of biodiesel in fuel blends.     

加强高速公路沥青路面施工质量确保沥青路面平整度

分析了影响沥青路面平整度的主要原因,并介绍了应采取的质量保证措施,以保证沥青路面施工质量。     

高速公路路面平整度施工控制

通过自己多年的路面施工实践经验,详细阐述了高速公路各结构层在施工过程中平整度好坏的影响因素,并针对出现的问题提出了自己的一些处理措施。     

盘海营高速公路SMA路面试验段施工

SMA路面同以往的密级配沥青混凝土路面相比,在抗车辙、防水损害、耐久性、抗滑等指标方面均有显著提高,故此对SMA路面的施工特点、施工工艺行总结分析,对今后该类型路面施工有较好的指导意义及使用价值.