面向大规模道路网的最短路径近似算法

节点重要性对大规模道路网下最短路径的计算有着重要影响。本文提出了顾及节点重要性的最短路径估计方法,该方法基于Critic方法与复杂网络理论评价节点的重要性,结合限制策略实现网络划分,通过层次结构网络的构建,实现大规模道路网数据的有效化简和最短路径的快速有效计算。试验结果表明,该方法能够使中心节点均衡地分布于网络,更好地均衡划分后子网络的规模;随着限制参数的增大,网络规模逐渐降低,查询精度最高达到1.026,相比于单一指标和无限制参数的方法,本文方法显著降低了网络的规模,在最短路径的近似计算上保持了较高的准确性,为大规模复杂网络的近似分析提供分析思路。     

基于数据库实例的最短路径算法及其在WebGIS环境实现

最短路径算法是GIS空间分析研究的热点问题。本文将最短路径的实时计算转换为预计算,利用关系数据库将最短路径计算过程和结果实例化,并在W ebGIS环境下实现了城市任意两点之间最短路径的快速计算和响应。     

Dijkstra最短路径分析算法的优化实现

最短路径问题是地理信息系统的关键问题,传统Dijkstra算法在求解节点间最短路径时,对已标识节点以外的大量节点进行了计算,从而影响了算法的速度。因而对其算法进行优化是很有必要。本文在对传统Dijkstra算法分析的基础上,对其进行了优化,优化算法只对最短路径上节点的邻居做了处理,而不涉及其他节点,并利用Visual C++6.0开发平台编程进行了实验。实验表明,该算法是行之有效的。     

基于数据库实例的最短路径算法及其在WebGIS环境实现

最短路径算法是GIS空间分析研究的热点问题。本文将最短路径的实时计算转换为预计算，利用关系数据库将最短路径计算过程和结果实例化，并在WebGIS环境下实现了城市任意两点之间最短路径的快速计算和响应。     

校车最优路径规划算法

提出一个基于GIS网络分析的校车路径方案规划算法。算法采用Dijkstra最短路径算法结合道路网络拓扑分析。以高效利用各种资源为目的,通过限制搜索范围提高算法效率,并用空间分析选择最佳起始节点,计算将学区内路网上各乘车节点处的学生送至学校的最优路径方案。实验结果验证了该算法的高效性和有用性。     

一种基于最短优先的最短路径算法的实现

最短路径问题作为GIS分析中的一个主要内容而被广泛深入地进行研究。本文在设计一种网络数据结构的基础上, 通过一种基于节点与弧段标号的最短优先路径搜索策略, 设计并实现了一种结构简单、便于理解并且高效的最短路径求解算法。     

VC环境下最短路径算法的实现

设计了一种方便查找及显示最短路径的数据结构,对仅研究计算一条最短路径的Dijkstra算法加以了改进,并在VC下实现一个顶点到另一个顶点的所有最短路径的查找。     

改进Dijkstra算法的城市道路最短路径仿真研究

本文在分析Dijkstra算法基础上,考虑城市路网的特点及该算法在路径优化中的不足,提出一种基于双向搜索的Dijkstra改进算法,它可以减少路网节点的搜索范围和计算复杂度。仿真结果表明,改进算法在最短路径搜索中可使候选节点数减少15%～25%,当节点越多这种减少越明显,可提高搜索路径的实时性。     

改进Dijkstra算法的城市道路最短路径仿真研究

本文在分析Dijkstra算法基础上,考虑城市路网的特点及该算法在路径优化中的不足,提出一种基于双向搜索的Dijkstra改进算法,它可以减少路网节点的搜索范围和计算复杂度.仿真结果表明,改进算法在最短路径搜索中可使候选节点数减少15％～25％,当节点越多这种减少越明显,可提高搜索路径的实时性.     

在ArcGIS矢量图中搜寻最短路径的实现

最短路径问题是地理网络分析中的重要问题之一,具有重要的应用价值。搜索最短路径的方法很多,在研究了各种方法后,本文提出了在ArcGIS矢量图中搜索最短路径的新方法。首先,提取经过ArcGIS简单处理的矢量图的信息,然后,借助Floyd算法,用MATLAB建模来提取节点间的最短路径,最后根据模型运算的结果在矢量图中绘出最短路径。试验证明,该方法操作简单,效果良好。     

基于二叉树的启发式搜索算法改进

最短路径是现代物流配送研究中热点问题之一,在分析传统启发式搜索算法的基础上,针对算法在路径优化中存在的不足,提出基于二叉树优化启发式搜索算法（A＊）实现所需结点之间最短路径查询,在引入已知的全局信息条件下选择下一个被检查的结点,并根据用户给出的起始顶点与目标顶点以及搜索的角度查找最短路径,从而搜索可能性较大的结点,提高搜索过程的效率.实验表明,基于二叉树的A＊比A＊效率提高11％～26％.     

A Hybrid Link‐Node Approach for Finding Shortest Paths in Road Networks with Turn Restrictions

Turn restrictions, such as ‘no left turn’ or ‘no U‐turn’, are commonly encountered in real road networks. These turn restrictions must be explicitly considered in the shortest path problem and ignoring them may lead to infeasible paths. In the present study, a hybrid link‐node Dijkstra's (HLND) algorithm is proposed to exactly solve the shortest path problem in road networks with turn restrictions. A new hybrid link–node labelling approach is devised by using a link–based labelling strategy at restricted nodes with turn restrictions, and a node‐based labelling strategy at unrestricted nodes without turn restrictions. Computational results for several real road networks show that the proposed HLND algorithm obtains the same optimal results as the link‐based Dijkstra's algorithm, while having a similar computational performance to the classical node‐based Dijkstra's algorithm.     

基于瞬时水深模型的最短时间航线自动生成算法

优化的海图航线设计是舰船安全、经济航行的先导和基础。本文提出了一种基于瞬时水深模型的最短时间航线自动生成算法。基于海图静态水深和海域潮位模型,构建瞬时水深模型,动态提取碍航区,并进行航线可行性分析;利用动态规划思想,进行最短时间路径搜索;采用矩形包络分析、相近节点搜索和冗余点删除等策略,进行航线优化。实验表明：本文所提算法,能动态分析航线可行性,搜索最短时间航线; 与传统的最短时间航线算法相比,所提算法可提取航行时间更短的航线;所提取的最短时间航线,与舰船航行的起始时间和舰船航速相关。     

A fast algorithm for finding K shortest paths using generalized spur path reuse technique

The problem of finding the K shortest paths (KSPs) between a pair of nodes in a road network is an important network optimization problem with broad applications. Yen's algorithm is a classical algorithm for exactly solving the KSP problem. However, it requires numerous shortest path searches, which can be computationally intensive for real large networks. This study proposes a fast algorithm by introducing a generalized spur path reuse technique. Using this technique, shortest paths calculated during the KSP finding process are stored. Accordingly, many shortest path searches can be avoided by reusing these stored paths. The results of computational experiments on several large‐scale road networks show that the introduced generalized spur path reuse technique can avoid more than 98% of shortest path searches in the KSP finding process. The proposed algorithm speeds up Yen's algorithm by up to 98.7 times in experimental networks.     

一种基于局部激光高速节点骨干网络的星间链路拓扑规划与仿真优化方法

激光星间链路具有传输容量大和传输速率高等技术特点,具有激光星间链路功能的卫星节点可以在激光-微波混合星间链路网络中作为高速骨干网节点. 如何部署这些高速节点,使得构建的卫星网络拓扑达到最优目标,是星间链路由微波到激光过渡发展中的一个研究重点. 以包括24颗中圆地球轨道（MEO）、3颗地球同步轨道（GEO）和3颗倾斜地球同步轨道（IGSO）卫星的导航卫星星座为应用场景,在高速节点数量固定的条件下,综合几何可视性、星间距离和工程约束等约束条件, 以卫星网络接入节点到目的节点的平均端到端时延最小为优化目标,建立数学模型,提出一种基于多源最短路径策略的混合星间链路网络高速节点选取算法,求解局部激光高速节点骨干网络的最优拓扑结构. 仿真结果表明:本文算法得到的局部激光高速节点骨干网络拓扑结构能使整网传输时延更小,通信性能更佳.      

An optimum vehicular path algorithm for traffic network based on hierarchical spatial reasoning

Human beings’ intellection is the characteristic of a distinct hierarchy and can be taken to construct a heuristic in the shortest path algorithms. It is detailed in this paper how to utilize the hierarchical reasoning on the basis of greedy and directional strategy to establish a spatial heuristic, so as to improve running efficiency and suitability of shortest path algorithm for traffic network. The authors divide urban traffic network into three hierarchies and set forward a new node hierarchy division rule to avoid the unreliable solution of shortest path. It is argued that the shortest path, no matter distance shortest or time shortest, is usually not the favorite of drivers in practice. Some factors difficult to expect or quantify influence the drivers’ choice greatly. It makes the drivers prefer choosing a less shortest, but more reliable or flexible path to travel on. The presented optimum path algorithm, in addition to the improvement of the running efficiency of shortest path algorithms up to several times, reduces the emergence of those factors, conforms to the intellection characteristic of human beings, and is more easily accepted by drivers. Moreover, it does not require the completeness of networks in the lowest hierachy and the applicability and fault tolerance of the algorithm have improved. The experiment result shows the advantages of the presented algorithm. The authors argued that the algorithm has great potential application for navigation systems of large-scale traffic networks.