四象限变频器理论研究

分析了四象限变频器的研究现状,介绍了四象限变频器拓扑结构和工作原理的相关内容,为后续的研究提供了参考。     

Train Control to Reduce Delays upon Service Disturbances at Railway Junctions

Train delay is one of the most important indexes to evaluate the service quality of the railway. Because of interactions among different trains, a delayed train may hinder subsequent trains scheduled on other lines at junction area. Trains may be forced to stop or decelerate, which consequently leads to the loss of run-time. This paper proposes a time-saving control method to recover the train delay as much as possible. In the proposed method, golden section search is adopted to identify the optimal train speed at the time of signal upgrade in the conflicting area, which enables the train to depart from the conflicting area as soon as possible. A heuristic method is then developed to attain the train control scheme to realize the optimal train speed at the time of signal upgrade in the conflicting area. Simulation study indicates that the proposed method enables the train to across the conflicting area with smaller run-time and therefore leads to larger delay reduction, in comparison with the traditional maximum speed control method and the green wave control method.     

极化方式及其在电子战中的应用

极化是描述电磁波的重要参量,文章介绍了天线各种极化的特点,并通过两个实例,论述了电子战中极化工作方式的选择,阐述了极化信息在电子对抗中的作用。     

我国高速公路管理体制的反思与构建

推进具有中国特色的高速公路管理体制建设对于我国高速公路的健康持续发展具有重要意义。当前我国高速公路管理体制各异,管理水平参差不齐,直接影响到高速公路经济效益和社会效益的实现。因此,在遵循一定原则的基础上,明确我国高速公路管理体制建设的总体思路和目标,采取具体措施以推进统一、规范、科学、精简、高效的高速公路管理体系和模式的建立健全。     

全站仪坐标法放样公路路基边线

利用全站仪三维坐标测量功能,在公路路基边线放样现场实测一估计点的坐标,以该点为引数,反算出该点对应的路线中桩点桩号。之后,结合设计资料计算出路堑或路堤边桩与中桩的计算距离,再在放样现场进行比较和相应调整,最终确定路基边桩的准确位置。放样速度快、精度高,简便实用。