Theory of safety surrogates using vehicle trajectories in macroscopic and microscopic settings: Application to dynamic message signs controlled traffic at work zones

This paper presents a new mathematical framework for obtaining quantitative safety measure using macroscopic as well as microscopic traffic data. The safety surrogate obtained from the macroscopic data is in terms of analysis performed on vehicle trajectories obtained from the macroscopic data. This method of obtaining safety measure can be used for many different types of applications. The safety surrogate for the traffic dynamics are developed in terms of a new concept of Negative Speed Differentials (NSD) that involve a convolution of vehicle speed function obtained from vehicle trajectories and then performing the integration of the square of the output for its negative values. The framework is applicable to microscopic traffic dynamics as well where we can use car following models for microscopic dynamics or the LWR model for macroscopic dynamics. This paper then presents the use of this new safety surrogate on the development of a feedback control law for controlling traffic in work zones using Dynamic Message Signs. A hybrid dynamics model is used to represent the switching dynamics due to changing DMS messages. A feedback control design for choosing those messages is presented as well as a simple simulation example to show its application.     

Multi-criteria optimization of traffic signals: Mobility,safety, and environment

Two-dimensional multi-objective optimizations have been used for decades for the problems in traffic engineering although only few times so far in the optimization of signal timings. While the other engineering and science disciplines have utilized visualization of 3-dimensional Pareto fronts in the optimization studies, we have not seen many of those concepts applied to traffic signal optimization problems. To bridge the gap in the existing knowledge this study presents a methodology where 3-dimensional Pareto Fronts of signal timings, which are expressed through mobility, (surrogate) safety, and environmental factors, are optimized by use of an evolutionary algorithm. The study uses a segment of 5 signalized intersections in West Valley City, Utah, to test signal timings which provide a balance between mobility, safety and environment. In addition, a set of previous developed signal timing scenarios, including some of the Connected Vehicle technologies such as GLOSA, were conducted to evaluate the quality of the 3-dimensional Pareto front solutions. The results show success of 3-dimensinal Pareto fronts moving towards optimality. The resulting signal timing plans do not show large differences between themselves but all improve on the signal timings from the field, significantly. The commonly used optimization of standard single-objective functions shows robust solutions. The new set of Connected Vehicle technologies also shows promising benefits, especially in the area of reducing inter-vehicular friction. The resulting timing plans from two optimization sets (constrained and unconstrained) show that environmental and safe signal timings coincide but somewhat contradict mobility. Further research is needed to apply similar concepts on a variety of networks and traffic conditions before generalizing findings.     

谈港口国船舶污染物接收设施问题报告的处置

文中探讨了一起国际航行船舶关于港口国船舶污染物接收设施问题报告的调查情况,介绍了此次船舶污染物接收设施问题报告的原因分析及采取的措施,并向接收设施的提供者和使用者给出了优化建议,明确了各有关部门在港口国船舶污染物接收设施履约工作上的重点。     

基于模糊层次的铁路混装货物装运安全评价研究

随着客户运输需求的多样化升级,采用铁路混装货物装运模式在提升铁路运输效率、吸引多样货源等方面相较于单一品名装运显示出一定的优越性,同时混装货物装运面临的安全压力相较于单一品名装运出现骤增。为保障铁路混装货物装运安全,在阐述混装货物装运特点及安全控制要点的基础上,从"人防""物防""技防"3方面构建混装货物装运安全评价指标体系,采用层次分析法确定各指标权重,并利用模糊综合评价法对铁路混装货物装运安全进行评价,通过实例验证该评价方法的实用性及有效性,为铁路混装货物装运安全评价提供依据。     

Full six degrees of freedom coupled dynamic simulation of ship collision and grounding accidents

By taking advantage of the user-defined load subroutine (loadud) and the user common subroutine (usercomm) in LS-DYNA, the authors proposed a new coupled approach for simultaneously calculating structural damage and the planar 3DOF ship motions in ship collisions. The coupled procedure aimed at predicting the detailed structural damage together with reasonable global ship motions. This paper extends the method to consider the full 6DOF ship motions; thus, ship collision as well as grounding accidents can be properly handled. This method is particularly useful for design purposes because the detailed ship hull profile is not needed.A traditional ship maneuvering model is used for the in-plane surge, sway and yaw degrees of freedom with a series of nondimensional coefficients determined from experiments. It is assumed that the out-of-plane degrees of freedom are not coupled with the in-plane ship motions, and there is no coupling among roll, pitch and heave motions. The implementation is verified through free decay tests, and the obtained natural periods show good agreement with theoretical results.Several collision and grounding cases are simulated in which a supply vessel crashes into rigid plates with different orientations. The effects of the roll motion, the heave and pitch motions and the full 6DOF motions are studied. The results are compared with those from a 6DOF decoupled method. Ship motions through the proposed method compare reasonably well with SIMO results. It is found that several consecutive impacts may occur in the simulation of one collision case due to the periodic motions. This is not taken into account in the decoupled method, which makes this method unconservative.     

轨道安全监测中传感器优化配置研究

为了研究轨道结构安全监测中传感器的合理配置方法,确保城市轨道交通安全运营,通过建立桥上交叉渡线道岔模型和钢轨应变传递误差最小的目标函数,提出传感器测点选择依据和监测方案评价标准,保证监测方案的经济性、合理性。结论表明:模型数据曲线可以指导监测系统的测点位置选择;随着传感器测点数量增加,监测误差逐渐减小,但在误差比率的"拐点"后增加单位个数传感器带来的收益降低;通过建立误差最小准则的目标函数,结合误差指标可以评价和优化传感器布设方案;钢轨位移、附加力等指标的监测方案也可以通过本文方法确定。     

试论船舶电气图纸审查的基本方法与注意要点

文章根据船舶电气图纸审查工作经验对船舶电气图纸审查的目的和意义、审查依据、送审图纸目录、审查要求等内容进行了归纳与总结,介绍了电气图纸审查的基本方法与注意要点,提出图纸审查过程中应注意的几个问题。     

关于高速公路交通安全设施的设置

交通安全设施对减轻事故的严重度,排除各种纵、横向干扰,提高道路服务水平,提供视线诱导,增强道路景观等起着重要的作用,属于道路的基础设施.     

舰船电力系统保护性能优化的自适应算法

为满足舰船电力系统保护在快速性和选择性方面的要求,提出保护性能优化模型,根据电力系统的运行方式、拓扑结构和故障类型的变化,实时在线计算并修改保护整定值的自适应保护方法。将快速性和选择性指标作为保护性能综合指标的基本元素,采用模拟退火粒子群算法进行优化,最终实现不同运行工况下保护性能最优的整定值自适应调整。并在PSCAD/EMTDC软件中建立包含自适应保护算法的舰船电力系统保护仿真模型,仿真结果证明所提方法可有效提高系统保护性能。     

Benefit of speed reduction for ships in different weather conditions

Currently, the shipping industry is facing a great challenge of reducing emissions. Reducing ship speeds will reduce the emissions in the immediate future with no additional infrastructure. However, a detailed investigation is required to verify the claim that a 10% speed reduction would lead to 19% fuel savings (Faber et al., 2012).This paper investigates fuel savings due to speed reduction using detailed modeling of ship performance. Three container ships, two bulk carriers, and one tanker, representative of the shipping fleet, have been designed. Voyages have been simulated by modeling calm water resistance, wave resistance, propulsion efficiency, and engine limits. Six ships have been simulated in various weather conditions at different speeds. Potential fuel savings have been estimated for a range of speed reductions in realistic weather.It is concluded that the common assumption of cubic speed-power relation can cause a significant error in the estimation of bunker consumption. Simulations in different seasons have revealed that fuel savings due to speed reduction are highly weather dependent. Therefore, a simple way to include the effect of weather in shipping transport models has been proposed.Speed reduction can lead to an increase in the number of ships to fulfill the transport demand. Therefore, the emission reduction potential of speed reduction strategy, after accounting for the additional ships, has been studied. Surprisingly, when the speed is reduced by 30%, fuel savings vary from 2% to 45% depending on ship type, size and weather conditions. Fuel savings further reduce when the auxiliary engines are considered.