共查询到18条相似文献,搜索用时 93 毫秒
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地图道路的提取及道路网的生成是电子导航、城市规划、电力、通讯等应用的关键.论文基于数学形态学与节点分析的要素提取算法,通过对地形图进行预处理和道路节点的判断,实现了二值化地形图道路的提取.在分析最短路径问题对道路信息需求的基础上,进行了道路网拓扑结构的构建.通过原型系统的实验证明,上述算法有效可行. 相似文献
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基于边缘检测的SAR图像平行线特征提取算法 总被引:1,自引:0,他引:1
针对传统平行线定义的局限性,本文提出了一种平行线对模型,并以该模型为核心,设计了一种基于边缘检测的SAR(SyntheticAperture Radar,SAR)图像平行线特征提取算法.在图像经过滤波预处理后,首先采用具有恒虚警特性的ROEWA(Ratio of Exponentially Weighted Averages,ROEWA)算子得到边缘检测图,再利用提出的平行线基元提取算法进行检测,最后基于启发式连接的思想连接断点.实验结果表明,该算法能有效地提取SAR图像中的平行线性结构,可以进一步应用于道路网、机场跑道、河流等大型组合线性目标的自动识别中. 相似文献
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The objective of an accident-mapping algorithm is to snap traffic accidents onto the correct road segments. Assigning accidents onto the correct segments facilitate to robustly carry out some key analyses in accident research including the identification of accident hot-spots, network-level risk mapping and segment-level accident risk modelling. Existing risk mapping algorithms have some severe limitations: (i) they are not easily ‘transferable’ as the algorithms are specific to given accident datasets; (ii) they do not perform well in all road-network environments such as in areas of dense road network; and (iii) the methods used do not perform well in addressing inaccuracies inherent in and type of road environment. The purpose of this paper is to develop a new accident mapping algorithm based on the common variables observed in most accident databases (e.g. road name and type, direction of vehicle movement before the accident and recorded accident location). The challenges here are to: (i) develop a method that takes into account uncertainties inherent to the recorded traffic accident data and the underlying digital road network data, (ii) accurately determine the type and proportion of inaccuracies, and (iii) develop a robust algorithm that can be adapted for any accident set and road network of varying complexity. In order to overcome these challenges, a distance based pattern-matching approach is used to identify the correct road segment. This is based on vectors containing feature values that are common in the accident data and the network data. Since each feature does not contribute equally towards the identification of the correct road segments, an ANN approach using the single-layer perceptron is used to assist in “learning” the relative importance of each feature in the distance calculation and hence the correct link identification. The performance of the developed algorithm was evaluated based on a reference accident dataset from the UK confirming that the accuracy is much better than other methods. 相似文献
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The optimal route between a given origin and destination needs to be computed in a fast and efficient manner in dynamic route guidance systems. Conventional routing algorithms have been found to be inadequate when applied directly to large road networks. Algorithms based on the concept of hierarchical abstraction make use of the knowledge about the road network to reduce search and provide near-optimal solutions. A generic procedure is presented for organising a given road network as a multiple-layer hierarchy. An efficient hierarchical routing algorithm is proposed, which breaks down the route search into a number of individual searches in small sub-networks. The algorithm incorporates a heuristic layer-switching technique to improve its performance without compromising the accuracy. The hierarchical routing algorithm was tested on the road network of Singapore and the solutions were found to be comparable to the optimal least-cost paths. 相似文献
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This study develops a neural network (NN) model to explore the nonlinear relationship between crash frequency and risk factors. To eliminate the possibility of over-fitting and to deal with the black-box characteristic, a network structure optimization algorithm and a rule extraction method are proposed. A case study compares the performance of the trained and modified NN models with that of the traditional negative binomial (NB) model for analyzing crash frequency on road segments in Hong Kong. The results indicate that the optimized NNs have somewhat better fitting and predictive performance than the NB models. Moreover, the smaller training/testing errors in the optimized NNs with pruned input and hidden nodes demonstrate the ability of the structure optimization algorithm to identify the insignificant factors and to improve the model generalization capacity. Furthermore, the rule-set extracted from the optimized NN model can reveal the effect of each explanatory variable on the crash frequency under different conditions, and implies the existence of nonlinear relationship between factors and crash frequency. With the structure optimization algorithm and rule extraction method, the modified NN model has great potential for modeling crash frequency, and may be considered as a good alternative for road safety analysis. 相似文献
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基于图论网络最大流理论基础,建立了一种改进的网络最大流模型。首先,根据最基本的网络最大流模型,采用Ford-Fulkerson算法求解出理论最大通行能力为46人/s;其次,考虑通行的道路选择性,建立最短路模型,利用Dijkstra算法计算各个单源到各个单汇的最短路径,并通过A*算法排除与最短距离相差较大的路径,从而筛选出有效路径;然后,利用最短路模型结果加强原模型中的约束条件,利用单纯形法求解出实际最大通行能力为23人/s;最后,建立以道路扩宽成本最低为目标函数的线性规划模型对道路进行优化改造。研究结果表明,现有道路设计能够满足道路通行需求,若需提高道路通行能力且要求道路改造最小,可以适当扩宽路网中的关键道路。 相似文献
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针对煤矿掘进机器人履带行驶系统工作环境恶劣,载荷无法直接有效获取这一工程实际问题,提出了基于遗传神经网络的振动信号载荷识别方法。构建了遗传算法(GA)优化BP(back propagation)神经网络载荷识别模型,采用路试法试验采集了履带小车的5组振动加速度数据和单组应力载荷数据,探讨路面不平度频率和驱动轮啮频等对履带车振动和应力载荷的影响规律;借助快速傅里叶变换(FFT)对原始应力载荷数据进行去噪处理,依据履带小车行驶平顺性指标,利用sym8小波函数对振动加速度信号进行5层特征提取以提高载荷识别的精度,然后将5组小波变换分解的加速度数据和滤波后的应力载荷数据分别作为GA-BP神经网络的输入和输出进行训练及验证,揭示了履带行驶系统运动过程中振动与应力载荷之间的关系。研究结果表明,路面不平度频率、驱动轮啮频及转频为小车振动的主要频率成分,路面不平度引起的振动频率为13.765 Hz,驱动轮啮频为68.25 Hz,转频为3.25 Hz。多组试验得到的BP神经网络最佳隐含层神经元数为63,GA-BP神经网络识别的应力载荷与期望应力载荷具有较高吻合度,相对误差为4.5%,验证了该方法的有效性... 相似文献
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Binu Sara Mathew Kuncheria P. Isaac 《International Journal of Pavement Engineering》2014,15(4):352-360
The objective of this paper is to develop an optimised maintenance strategy for the rural road network of Kerala state. This is accomplished with the development of a bi-objective deterministic optimisation model which simultaneously satisfies the objectives of both minimisation of total maintenance cost and maximisation of performance of the road network. The model is capable of planning the maintenance activities over a multi-year planning period. The performance of the road network is accounted using the composite index, namely Pavement Condition Index. The constraint-based genetic algorithm was used as the optimisation tool since it very well takes care of the combinatorial nature of the network-level pavement maintenance programming. The applicability of the model is illustrated using a case study for the rural road network of Kerala state in India. The effort made through this research work to develop a suitable Pavement Maintenance and Management System for rural road network can lead to the proper maintenance and upkeep of the rural roads, thereby triggering a positive impact on the Indian economy. 相似文献
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Weiwei Liu Yang Tang Fei Yang Chennan Zhang Dun Cao Gwang-jun Kim 《计算机、材料和连续体(英文)》2020,65(3):2511-2527
Intelligent Transportation System (ITS) is essential for effective identification
of vulnerable units in the transport network and its stable operation. Also, it is necessary
to establish an urban transport network vulnerability assessment model with solutions
based on Internet of Things (IoT). Previous research on vulnerability has no congestion
effect on the peak time of urban road network. The cascading failure of links or nodes is
presented by IoT monitoring system, which can collect data from a wireless sensor
network in the transport environment. The IoT monitoring system collects wireless data
via Vehicle-to-Infrastructure (V2I) channels to simulate key segments and their failure
probability. Finally, the topological structure vulnerability index and the traffic function
vulnerability index of road network are extracted from the vulnerability factors. The two
indices are standardized by calculating the relative change rate, and the comprehensive
index of the consequence after road network unit is in a failure state. Therefore, by
calculating the failure probability of road network unit and comprehensive index of road
network unit in failure state, the comprehensive vulnerability of road network can be
evaluated by a risk calculation formula. In short, the IoT-based solutions to the new
vulnerability assessment can help road network planning and traffic management
departments to achieve the ITS goals. 相似文献