本文急需两篇论文,不好意思,俺金币不多,只能一篇10个金币了,请帮个忙吧!谢谢!(1)题目:Optimal Pacing of Trains in Freight Railroads: Model Formulation and Solution 作者:David Kraay, Patrick T. Harker, Bintong Chen ; (2 题目:Simulator for studying operational and power- supply conditions in rapid-transit railways