A simplified pneumatic model for air brake of passenger trains

Braking system performance is relevant for both railway safety and network optimization. Most trains employ air brake systems;air brake systems of freight trains mostly cannot achieve a synchronous application of brake forces, which is usually customary for passenger trains. The paper generalizes a previous air brake pneumatic model to passenger trains and describes the needed modifications. Among them, the way the pressure reduces in the brake pipe is generalized. Moreover, this paper reports an analytical bi-dimensional function for calculating the nozzle diameter equivalent to the electro-pneumatic(EP) or the electronically controlled pneumatic(ECP)brake valve as a function of the wagon length and the time to vent the brake pipe locally. The numerical results of the new model are compared against several experimental tests of high-speed passenger trains of Trenitalia, namely ETR500 and ETR1000. The model is suitable to be integrated into the UIC software TrainDy, aiming to extend its computational field to passenger trains and to simulate the safety of trains during a recovery.

移动闭塞条件下重载铁路列车流特性研究

移动闭塞系统是我国重载铁路未来发展的关键技术。借鉴道路交通流理论,建立描述流量、密度及速度关系的铁路宏观基本图,用以分析重载列车流的基本特性及运行现象。建立移动闭塞条件下列车优化速度跟驰模型,以大秦铁路为背景进行仿真模拟,根据模拟结果绘制重载列车流仿真Q-K-V关系图,并与理论基本图进行对比分析,证明了仿真模型的可靠性。在此基础上,研究不同列车长度、不同坡度、不同限速以及采用电控空气制动条件下重载列车流的特性和对线路能力的影响。进一步研究移动闭塞条件下重载列车流冲击波产生的机理及传播规律,为重载运输列车流的管控提供了理论基础。

专利激增的驱动因素及机理分析

本文提出了一个具备包容性和系统性的专利激增驱动因素三维分析模型,即,要素-能力-倾向(ECP)模型,任何驱动因素均至少通过一个维度发挥作用。基于ECP模型,本文同时采用系统力学方法明确了各类驱动因素作用于专利增长的路径和机理。本研究的重要政策启示在于,良好的政策应当首先从提升要素投入以及创新能力入手,而非单方面促进专利倾向的提高。