首页> 外文OA文献 >Time-dependent networks : data representation techniques and shortest path algorithms with applications to transportation problems
【2h】

Time-dependent networks : data representation techniques and shortest path algorithms with applications to transportation problems

机译:时间依赖网络:数据表示技术和最短路径算法,适用于运输问题

摘要

In this thesis, we develop methods for the following problems: the representation of discrete-time dynamic data, and the computation of fastest paths in continuous-time dynamic networks. We apply these methods for the following application problems: storage and communication of discrete-time dynamic transportation network data, and computation of fastest paths in traffic networks with signalized intersections. These problems are at the heart of realtime management of transportation networks equipped with information technologies. We propose a representation (called the bit-stream representation) method for nondecreasing discrete-time dynamic functions as a stream of 0 and 1 bits. We show that this representation is 12 times less memory consuming than the classical representation for such data, where the function value at each time-instant is stored as an L-bit integer. We exploit this representation to efficiently store and represent travel-time data in discrete-time dynamic transportation networks. Since the bit-stream representation requires lesser memory space, it also leads to lesser communication-time requirements for applications involving communication of such data. We adapt a classical dynamic one-to-all fastest path to work on bit-streams and show that this leads to savings of up to 16-times in over-all communication and computation times. This holds the potential to impact the development of efficient high performance computer implementations of dynamic shortest path algorithms in time-dependent networks. We model travel-times in dynamic networks using piece-wise linear functions. We consider the one-to-all fastest path problem in a class of continuous-time dynamic networks. We present two algorithms: Algorithm OR, that is based on a conceptual algorithm known in the literature; and Algorithm IOT-C, that is developed in this thesis. We implement the two algorithms, and show that Algorithm IOT-C outperforms Algorithm OR by a factor of two. We study the application problem of computing fastest paths in traffic networks with signalized intersections. We use a piece-wise linear link travel-time dynamic network model to address this problem, and demonstrate that this model is more accurate than discrete-time models proposed in the literature. Some of the implemented algorithms are applied to solve variants of the one-to-all fastest path problem in traffic networks with signalized intersections, and study the computational performance of these implementations.
机译:本文研究了以下问题的解决方法:离散时间动态数据的表示以及连续时间动态网络中最快路径的计算。我们将这些方法应用于以下应用问题:离散时间动态交通网络数据的存储和通信,以及带有信号交叉口的交通网络中最快路径的计算。这些问题是配备信息技术的运输网络实时管理的核心。我们提出了一种不减少离散时间动态函数为0和1位流的表示方法(称为位流表示法)。我们表明,对于此类数据,这种表示方式的存储消耗比经典表示形式少12倍,在这种情况下,每个时间点的函数值都存储为L位整数。我们利用这种表示法来有效地存储和表示离散时间动态运输网络中的旅行时间数据。由于比特流表示需要较小的存储空间,因此对于涉及此类数据通信的应用程序,也导致对通信时间的要求较小。我们采用了一条经典的动态的“一对一”最快路径来处理比特流,并表明这可以节省多达16倍的总体通信和计算时间。这有可能影响依赖时间的网络中动态最短路径算法的高效高性能计算机实现的开发。我们使用分段线性函数对动态网络中的旅行时间进行建模。我们考虑一类连续时间动态网络中的一对多最快路径问题。我们提出两种算法:算法OR,基于文献中已知的概念算法;本文开发的算法IOT-C。我们实现了这两种算法,并表明算法IOT-C的性能优于算法OR的两倍。我们研究了在有信号交叉口的交通网络中计算最快路径的应用问题。我们使用分段线性链接旅行时动态网络模型来解决此问题,并证明该模型比文献中提出的离散时间模型更准确。一些已实现的算法被用于解决带有信号交叉口的交通网络中最快的全路径路径问题的变体,并研究这些实现的计算性能。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利

客服邮箱:kefu@zhangqiaokeyan.com

京公网安备:11010802029741号 ICP备案号:京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有
  • 客服微信

  • 服务号