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981.
Finding the K-shortest paths in timetable-based public transportation systems is an important problem in practice. It has three typical variants: the K-earliest arrival problem (K-EAP), the K-shortest travel time problem (K-STTP), and the K-minimum number of transfers problem (K-MNTP). In this article we show that these problems can be solved efficiently by first modeling the timetable information with the time-expanded approach, then applying the Martins and Santos (MS) algorithm. Then we model the timetable information with the time-dependent approach and propose a modified version of the MS algorithm for solving the K-EAP. Experimental results on real-world data show that for K smaller than 100, which is enough for most applications, the execution times of the MS algorithm for the problems in the time-expanded model are less than 100 ms on a server with a 1.86-GHz central processing unit (CPU) and 4 GB of memory. For solving the K-EAP the modified MS algorithm in the time-dependent model is even more efficient (about three times faster for K ≤ 100) than the original algorithm in the time-expanded model. Our results imply the great potential of the MS algorithms in practical transportation service systems. 相似文献
982.
Statistics from the databases of various countries and international organizations show that road accident rates and fatalities have fallen since the 1970s. With demographic changes taking place in many developed countries, however, accident and accident-risk patterns have changed in the last two decades. This study aims to introduce a new approach to cross-sector cooperation with the hope of making road safety more holistic and sustainable. The authors compare the road safety policies of three selected countries based on various categories, using a simple quantitative method. The results show some fragmentation within the policies, illustrating the need for a new road safety approach. The effort to reduce road traffic accidents by 50% by the year 2020 has also increased the pressure on stakeholders to meet this goal. This paper's contribution toward the 2020 goal lies in its recommendation of a new approach to road safety that will enlighten stakeholders on probable missing links in road safety. 相似文献
983.
针对传统汽车照明系统只能用手动控制,在路况复杂或者环境恶劣的情况下不能及时有效地提供良好照明的问题,文章介绍了一种自适应车灯前照明控制系统(AFS)并对其控制方法进行了研究。运用模糊控制理论并使用MATLAB/SIMUuNK软件中的FUZZY模块,对水平和垂直方向上的车灯偏转设计了模糊控制器。指出AFS应用前景广阔,模糊控制技术可以为将来智能车灯的发展提供参考。 相似文献
984.
公路路面检测数据是路面使用性能评价和养护管理决策的基础,探讨了公路路面智能检测技术未来可能的发展方向,介绍了国内外公路路面智能检测技术发展的现状并指出了存在的问题。 相似文献
985.
随着燃油价格持续上涨及企业用工成本上升,通过智能网联技术实现车队的智能化管理从而帮助物流企业降本增效成为人们关注的焦点。文章基于车联网采集的高分辨率车辆行驶数据,从经济性、安全性角度出发提取8个驾驶行为特征指标,利用熵权法确定各指标权重,再采用TOPSIS模型计算实现了对各行程司机驾驶行为的评价,实例计算结果表明,该方法能客观、有效地评价高速干线物流卡车司机驾驶行为,对物流企业开展生态驾驶培训、改善车队燃油经济性、驾驶安全性具有重要的参考价值。随着智能网联汽车的到来,该方法还可以为自动驾驶车速规划提供参考。 相似文献
986.
987.
智能网联背景下的车联网数据分析与应用对提升交通智能化有重要影响。为了加快交通智能化进程,文章对车联网数据应用过程中存在的数据冗余问题进行研究。以采集的车联网数据为研究对象,驾驶行为特点分类辨识为研究目标。采用相关分析与主成分分析方法对数据进行冗余筛选与降维,使用k-means聚类算法对驾驶行为特点进行分类辨识。研究结果表明,使用数据降维的方法可以降低车联网数据的相关冗余性,驾驶行为特点分类辨识结果表明其特点可分为三类驾驶行为。研究提升了车联网数据的应用价值,也为交通智能化提供了相关的支持。 相似文献
988.
智能交通系统研发历程与动态述评 总被引:1,自引:0,他引:1
对智能交通系统(ITS)进行了整体描述,回顾了美国、日本和欧洲的ITS发展历程,并结合其研发动态对国外ITS研发特点做出评述。介绍了国外ITS未来的建设目标,指出发达国家已经不是将ITS仅仅看成解决交通拥堵的工具,而是将其看作解决能源和环境问题的可选项,ITS的研发应注意与能源、出行权利以及交通安全的关系。最后,指出ITS发展需要实现真正的学科交叉和交融,并讨论了国内ITS未来发展的研究方向:注重信息技术应用条件下交通系统的描述方法以及交通系统的状态表达和人的行为研究。 相似文献
989.
990.
A self-tuning fuzzy PID (ST-FPID) control scheme is implemented within a joint interactive (Matlab/Simulink/Fluent) co-simulation framework for effective two degrees of freedom (2DOF) vortex-induced vibration (VIV) control of an elastically-mounted circular cylinder in laminar cross-flow of incompressible non-Newtonian power-law fluids based on the control action of a single transverse force actuator. The model-free controller, which systematically tunes the control parameters online in real time based on given rules, is well-known to be highly advantageous over the previously employed conventional PID controllers. It is particularly capable of handling the intricate non-linear dynamic effects inherent in the complex fluid rheology of non-Newtonian flow past the cylinder in presence of unmodeled system dynamics, high parametric uncertainties, diverse operational conditions, and time-varying external disturbances and control signals. Extensive numerical simulations reveal that the complex shear-thinning and shear-thickening behaviors of fluid viscosity can substantially influence the cylinder dynamic response, applied hydrodynamic forces, and flow structure. In particular, effectiveness and high performance of the adopted ST-FPID control strategy in substantial suppression of the high amplitude coupled 2DOF VIV of the elastically-mounted cylinder at selected critical reduced velocities in the lock-in region are established for a wide range of power-law index parameters (e.g., up to 83% reduction in RMS value of cylinder cross-flow displacement and up to 35% reduction in RMS value of cylinder in-line displacement for n=1and U* = 5 at Re = 100). Also, the vigorous action of the error-driven ST-FPID controller in forcing the high strength vortex shedding patterns of the uncontrolled cylinder out of the lock-in condition into the classical von Kármán vortex street of 2S-type mode of moderately weaker strengths is verified. 相似文献