Remote Sensing Applied to the Extraction of Road Geometric Features Based on Optimum Path Forest Classifiers, Northeastern Brazil

One of the principal difficulties related to road safety management in Brazil is the lack of data on road projects, especially those on rural roads, which makes it difficult to use road safety studies and models from other countries as a reference. Updating road networks through the use of hyperspectral remote sensing images can be a good alternative. However, accurately recognizing and extracting hyperspectral images from roads has been recognized as a challenging task in the processing of hyperspectral data. In order to solve the aforementioned challenges, Hyperion hyperspectral images were combined with the Optimum Forest Path (OPF) algorithm for supervised classification of rural roads and the effectiveness of the OPF and SVM classifiers when applied to these areas was compared. Both classifiers produced reasonable results, however, the OPF algorithm outperformed SVM. The higher classification accuracy obtained by the OPF was mainly attributed to the ability to better distinguish between regions of exposed soil and unpaved roads.

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 hierarchy 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.

改进蚁群算法的送餐机器人路径规划

蚁群算法拥有良好的全局性、自组织性、鲁棒性,但传统蚁群算法存在许多不足之处。为此,针对算法在路径规划问题中的缺陷,在传统蚁群算法的状态转移公式中,引入目标点距离因素和引导素,加快算法收敛性和改善局部最优缺陷。在带时间窗的车辆路径问题(vehicle routing problem with time windows,VRPTW)上,融合蚁群算法和遗传算法,并将顾客时间窗宽度以及机器人等待时间加入蚁群算法状态转移公式中,以及将蚁群算法的解作为遗传算法的初始种群,提高遗传算法的初始解质量,然后进行编码,设置违反时间窗约束和载重量的惩罚函数和适应度函数,在传统遗传算法的交叉、变异操作后加入了破坏-修复基因的操作来优化每一代新解的质量,在Solomon Benchmark算例上进行仿真,对比算法改进前后的最优解,验证算法可行性。最后在餐厅送餐问题中把带有障碍物的仿真环境路径规划问题和VRPTW问题结合,使用改进后的算法解决餐厅环境下送餐机器人对顾客服务配送问题。

Optimum Designing of Gas Distribution Networks of Ilam Province by Using GIS Network and Spatial Analysis

Undoubtedly, pipeline transport is considered as significant economical artery of country and national valuable resources, so it is necessary to use latest technologies, major standards and instructions and the best human resources in designing, operation and supervision in construction and also protection of it. Also, all authorities and involved of construction and operation of gas industries installation should observe safety criteria, health and environment and aware of them ever. In fact, in designing of these programs, in addition to technical and economical points, environmental characteristics should be considered in order to their construction has minimum damage to environment. On the other hand, common and traditional approaches of pipeline routing are based on using costly and time-consuming methods. In these methods, it is not easily to use all effective parameters in determining optimum way. According to capability of analysis of network spatial information systems in incorporation of spatial data, for using all effective parameters in routing, this environment is used, therefore weighted overlay analysis (Boleyn, index and fuzzy) and shortest path are modeled for finding optimum path of pipeline in GIS environment.

融合A^(*)与DWA算法的水面船艇动态路径规划

为解决水面船艇路径规划同时要求全局最优、实时避障和航迹安全可靠的问题,提出了一种基于融合A^(*)算法与动态窗口算法(DWA)的水面船艇路径规划方法。首先通过引入启发函数动态加权策略,提高A^(*)算法的搜索效率;然后综合考虑水面船艇的运动特性,采用一种路径转角节点角度削弱策略,减少转角,缩短全局路径长度;最后,基于全局因素影响与航迹安全约束对DWA算法的轨迹评价函数进行改进,并以全局路径提供子目标点引导DWA算法进行局部规划的方式完成算法融合。实验结果表明,融合算法相比于现有算法的总转向角度分别减少了45.6%、46.0%,验证了融合算法的有效性与可行性,并且相较于其他传统算法更具优越性。

Genetic algorithm for pareto optimum-based route selection

A quality of service （QoS） or constraint-based routing selection needs to find a path subject to multiple constraints through a network. The problem of finding such a path is known as the multi-constrained path （MCP） problem, and has been proven to be NP-complete that cannot be exactly solved in a polynomial time. The NPC problem is converted into a multiobjective optimization problem with constraints to be solved with a genetic algorithm. Based on the Pareto optimum, a constrained routing computation method is proposed to generate a set of nondominated optimal routes with the genetic algorithm mechanism. The convergence and time complexity of the novel algorithm is analyzed. Experimental results show that multiobjective evolution is highly responsive and competent for the Pareto optimum-based route selection. When this method is applied to a MPLS and metropolitan-area network, it will be capable of optimizing the transmission performance.

Optimal Path Finding Method Study Based on Stochastic Travel Time

Finding optimal path in a given network is an important content of intelligent transportation information service. Static shortest path has been studied widely and many efficient searching methods have been developed, for example Dijkstra’s algorithm, Floyd-Warshall, Bellman-Ford, A* et al. However, practical travel time is not a constant value but a stochastic value. How to take full use of the stochastic character to find the shortest path is a significant problem. In this paper, GPS floating car is used to detect road section’s travel time. The probability distribution of travel time is estimated according to Bayes estimation method. The combined probability distribution of a feasible route is calculated according to probability operation. The objective function is to find the route that has the biggest probability to arrive for desired time thresholds. Improved Genetic Algorithm is used to calculate the optimal path. The efficiency of the proposed method is illustrated with a practical example.

从“个体”到“社会”:农村互助养老服务的现实应对

农村互助养老服务是加快补齐农村养老服务短板的重要选择。基于农村互助养老服务的社会基础与生成逻辑,探讨农村互助养老服务的现实情境和核心动力,发现在社会变迁中,传统的地缘、血缘互助基础变得比较薄弱,而文化观念和社会资本作为“软约束”也难以全面发挥作用;农村老年人由于互助养老服务质量不高、回馈及时性不强、公平性难以有效衡量等问题,容易产生个体消极意识,进而提出立足现实需求、提升行动绩效,树立典型示范、重构社会资本,明确建设标准、建立制度保障,扩展资金来源、引导民众参与等农村互助养老服务的优化路径。

基于改进斥力模型的人工势场局部路径规划

针对传统人工势场算法易陷入局部最优点问题,提出一种改进斥力模型的人工势场方法,以提高自动驾驶汽车的安全性和稳定性。根据汽车速度方向和障碍物位置的相对关系以及障碍物与道路边界之间的距离,确定斥力偏转方向和偏转角度,避免汽车陷入局部最优;重新设计斥力场函数,把汽车避障安全距离引入到斥力作用范围中,在斥力函数中引入对数函数以及纵向相对距离调节因子,减小规划路径的曲率以及总转角。仿真计算结果表明:在应用改进斥力模型的人工势场方法进行局部路径规划时,斥力偏转角的选取对路径的稳定性和安全性有直接影响,合适的斥力偏转角能避免路径规划时出现局部最优。在多障碍物环境下车辆需要连续避障时,改进斥力模型所规划的路径总转角以及曲率峰值显著下降,能有效提高行驶安全性指标。

基于量子粒子群算法的无人水面艇路径规划

为了获得无人水面艇航行的最优路径,提高航行的安全性和航行路径的平滑度,提出一种基于量子粒子群优化的无人水面艇路径规划算法。首先,通过引入动态控制参数来提高该算法的寻优能力和搜索精度,并由测试函数验证其可行性;然后,在航行安全的前提下,以路径长度和路径平滑度为规划目标,在不同环境下对无人水面艇进行路径规划仿真实验。仿真结果表明,该算法在路径长度、路径平滑度及路径安全性方面表现较好,能找到全局最优路径。

光滑流道涡轮一维优化设计方法研究

为保证涡轮流道型线设计结果的光滑性,发展了一种先反设计初始流道,再进行光滑流道优化的轴流涡轮一维优化设计方法。设计方法针对涡轮中径处气动参数计算,求解一维流动控制方程,采用能量损失和速度损失系数模型,考虑冷气掺混和变比热影响;并结合了遗传算法,以提升等熵效率为目标,对流道几何、级功率分配和速度三角形参数进行优化。利用设计方法对两台文献涡轮进行了验证设计,对一台四级涡轮进行了优化设计。通过分析结果可知,设计方法可以有效设计光滑涡轮流道并提升等熵效率;流量、膨胀比和等熵效率计算较为准确,级载荷系数和流量系数分布计算较为可靠;叶排出口气流角误差绝对值的平均值在3.2°以内,马赫数误差绝对值的平均值在0.054以内;叶排损失随级数变化趋势基本准确。

采用多策略改进黑猩猩算法的农业机器人路径规划

为缩短农业机器人全局路径规划的长度和时间并获得更好的安全路径,提出了一种采用多策略改进黑猩猩算法(MIChOA)的路径规划方法。首先,对传统的黑猩猩算法(ChOA)进行改进,在种群初始化阶段引入佳点集策略提高种群的多样性;其次,根据黑猩猩实际寻优过程提出正态随机余弦收敛因子策略,平衡了算法全局勘探与局部开发能力;然后,在算法陷入局部最优停滞时采用贪婪竞争机制的停滞扰动策略,加快算法跳出局部最优并准确找到全局最优解;最后,利用标准测试函数验证MIChOA算法的寻优性能,建立了具有111个障碍物的环境栅格地图开展仿真实验,将MIChOA算法应用于农业机器人路径规划,并与其他4种较为优秀的改进ChOA算法进行比较。结果表明:MIChOA算法在单峰和复杂多峰函数上均具有较高的寻优精度、稳定的收敛性和良好的鲁棒性;MIChOA算法的路径搜索性能优于其他4种改进ChOA算法,其中路径长度缩短了28.01%,寻优时间和迭代次数分别减少了54.58%和85.87%。

求解多目标点路径规划问题的离散头脑风暴算法

为保证移动机器人以最短路径遍历多目标点,该文提出一种基于离散头脑风暴的多目标点路径规划算法。首先,考虑障碍物对路径规划的影响,将目标点间的最短避障距离作为评判依据,提高规划路径合理性。其次,针对传统离散头脑风暴算法在解决组合类优化问题时提前陷入局部最优的问题,提出一种启发式自适应路径优化策略,通过设计与迭代次数相关的适应度选择函数以及改进启发式交叉算子,增加路径多样性和提高算法收敛速度。基于栅格法建立地图模型,在不同环境地图中选取多个目标进行对比仿真,验证所提算法的有效性以及对不同环境的适应性。

基于最少换乘的公交最优路径算法的设计与实现

提出了基于最少换乘的公交最优路径理论,在此基础上设计了公交最少换乘的算法。由于算法本身的独特性,笔者将“图算法”部署到空间网络数据库中加以实现,利用数据库的快速查询、索引支持和在集合运算方面的优秀性能解决了算法的效率问题。同时还利用此类数据库系统对空间查询的支持,确保算法在求取最少换乘后可以兼顾距离最短的要求。

GPS软件接收机中的一种实用高灵敏度快速捕获算法

C/A码的捕获,在软件GPS接收机中的地位举足轻重.通常软件GPS接收机中没有专门用于相关运算的硬件部件,提高软件GPS接收机的捕获灵敏度的同时降低捕获的运算量,是软件接收机实用化的关键.利用先叠加再相关的方法,可以减少相关运算的次数,但必须考虑载波误差对相关函数峰值的影响.在此基础上,研究了数据预处理中,线性插值的参数选择问题,最后,提出了最佳路径算法,进行进一步的相关累积,在延长相干累积时间长度的同时,避免导航数据跳变对累积的影响,提高捕获的灵敏度.仿真结果表明,在信噪比SNR=-37dB的情况下,算法仍能捕获到所有卫星信号.实际接收的数据也表明,算法能明显增加捕获到的卫星数量.由于算法采用了多种措施来降低运算量,因此算法的运算量适中,非常适合在软件接收机中采用.

一种用于最优路径规划的改进遗传算法

设计了一种专门适用于路径规划的改进遗传算法.该算法根据最短路径问题的具体要求,将传统遗传算法中的编码、交叉、变异等操作均重新进行了定义,并且在进化过程中还能够自适应调节交叉和变异概率.仿真研究表明:改进的遗传算法具有较快的搜索速度和较高的搜索成功率,为实际车载导航系统中最优路径规划问题的解决提供了一种新方法.

最优路径森林分类算法综述

针对快速分类算法中最优路径森林(OPF)分类算法进行了研究,进行了OPF分类算法研究及应用现状的调查。OPF算法是近期兴起的一种基于完全图的分类算法,在一些公共数据集上与支持向量机(SVM)、人工神经网络(ANN)等算法的对比中,该算法能取得类似或更好的结果,速度更快。该算法不依赖于任何参数、不需要参数优化、不需要对各类别的形状作任何假设,能够处理多类问题,旨在全面系统地介绍OPF算法的研究及应用进展。

高速并联机械手抓放操作时间最优轨迹规划

提出了一种两平动自由度高速并联机械手——Diamond机构的时间最优轨迹规划方法.首先分析得到3次样条规律的操作空间轨迹误差与关节空间插扑节点间距的4次方成正比,然后确定出典型抓放操作轨迹各段的最大插补间距并获得抓放轨迹上一组最少轨迹点序列,有效提高了计算效率.在此基础上,以关节速度、加速度和其变化率,以及关节驱动转矩为约束条件,以抓放时间最短为目标,采用复合型优化法计算出电池分选操作的最大和最小单程运行时间分别为0.21 s和0.13 s,平均分选速度超过100次/min.该方法已成功应用于由4台Diamond机械手构成的高性能锂离子电池分选系统.

基于GIS的城市震后交通最优路径分析系统

在调查分析城市交通系统的震害情况和主要致灾因素的基础上,研究震后桥梁、路段和路边建筑物的破坏对交通通行即最优路径的影响,提出按路段通行概率水平、有效路段长度和路段宽度进行震后交通最优路径搜索的原则.采用ArcGIS Engine的Network Analysis接口技术编制具有交通系统管理、路径分析和搜索功能的决策信息系统,该系统可以根据震后抗震救灾的需要,为抗灾指挥与抢险、消防、医疗、物资运输和避震疏散等方面进行最佳路径的评价和仿真模拟.