Simulation of Train-Track Interaction with Stochastic Track Properties

A numerical method to simulate vertical dynamic interaction between a moving train and a railway track was extended to account for stochastic properties in the track structure. The numerical simulations are carried out in the time-domain with a moving mass model. Full-scale measurements in the field and laboratory experiments were carried out to obtain data for the stochastic track model. The values of the stochastic variables are thus chosen to correspond to real tracks. To investigate the influence of the randomness of selected stochastic parameters in the track structure, the Latin Hypercube sampling method with correlation control was used to generate stochastic realisations.     

混合动力汽车的研究现状与发展前景

简要分析了发展混合动力汽车的必然性。介绍了目前混合动力汽车的分类及国内外研究现状,分析了混合动力汽车的优缺点,并为混合动力汽车的发展指明了前景。     

多业务环境下切换优先算法的改进

切换是移动通信中充分利用有限频谱的一项关键技术。本文提出了在数据业务和话音业务环境下,基于混合信道分配(HCA)方案上的双先进先出(FIFO)排队算法:系统分别为切换语音呼叫和初始语音呼叫与数据呼叫分配了大小为Nh和No的排队空间,两队列均遵从FIFO法则;同时,为切换语音呼叫预留了可根据当前业务量调整数目的Cr个信道。通过与单FIFO排队算法和基于HCA的单FIFO排队算法的比较,可以看到本算法改善了系统的性能,更能适应高业务量小区的需要。     

基于IGBT及IGCT混合级联多电平变频器输出波形控制

针对传统两电平IGBT级联难提高输出电压及基于IGCT级联输出波形特性差的缺点,提出基于IGBT及IGCT混合级联多电平拓扑,采用单极性控制方法,在获得高输出电压的同时,使逆变器输出电压谐波分布于高频带,改善了输出电流品质。     

新能源客车燃油经济性提升分析研究

本文通过理论计算并结合实车测试数据,得出了12米城市公交车的燃油利用率,并以能量流的形式详细分析了汽车各部分的燃油消耗,最后阐述了混合动力车辆的节油措施及其效果。     

船用柴油机混合建模方法研究

鉴于单一的机理建模法和辨识建模法在船用柴油机建模领域都存在一定的不足,提出基于机理与网络辨识互补的船用柴油机混合建模方法。机理模型用来保证不同使用工况下的模型全局可信度,网络模型用来辨识系统中不可描述部分所带来的模型误差,二者通过互补形成混合模型。测试结果表明,采用混合建模方法可更好地反映船用柴油机的真实特性     

基于SX5256DH434PHEV型混合动力重型环卫车的电池管理系统浅谈

在全球能源危机的情况下,随着国际碳排放出口协定的实施,绿色清洁汽车已经成为发达国家当前汽车技术的发展方向,发达国家多数把锂离子电池作为EV、HEV、PHEV的新能源。由于汽车的复杂工况和锂离子电池电化学特性,一般需要完善的电池管理系统BMS(BATTERY MANAGEMENT SYSTEM),其作用是对锂离子电池电压、电流、温度、容量、电池的SOC荷电状态计量、电池与车体的绝缘状态等多种电池参数以CAN通讯的方式与车控电脑实时进行信息交换,确保电池的能量发挥到极致,使驾驶者能够随时掌握电池的工作状态,以保证电池的安全。BMS不仅是数字化智能电池系统的中枢神经,也是新能源汽车必不可少的关键部件。     

纤维高性能混凝土早龄期抗裂性能研究

在工作度和抗压强度研究的基础上,对比研究了不同纤维类型（玻璃纤维、聚丙烯纤维、钢纤维和混杂纤维）及掺量对高性能混凝土早龄期塑性开裂的影响.结果表明,单掺纤维或掺入混杂纤维可明显提高高性能混凝土的早龄期（1d）抗压强度;聚丙烯纤维和钢纤维可有效减小高性能混凝土早龄期塑性收缩裂缝的面积及宽度;二元混杂纤维比单一掺入玻璃纤维、聚丙烯纤维或钢纤维具有更好的限裂效果.     

Static and dynamic loading behavior of a hybrid foundation for offshore wind turbines

Considering the deficiencies of the traditional monopile foundation for offshore wind turbines (OWTs) in severe marine environments, an innovative hybrid foundation is developed in the present study. The hybrid foundation consists of a traditional monopile and a wide–shallow bucket. A series of numerical analyses are conducted to investigate its behavior under the static and dynamic loading, considering various loading eccentricities. A traditional monopile with the same steel volume is used as a benchmark. Although the monopile outperforms the hybrid foundation in terms of the ultimate moment capacity under each loading eccentricity, the latter can achieve superior or the same performance with nearly half of the pile length in the design loading range. Moreover, the horizontal load and moment are mainly resisted by the bucket and the single pile in the hybrid foundation respectively. The failure mechanism of both the hybrid foundation and the monopile is excessive rotation. In the rotation angle of 0.05 rad, the rotation center is located at the depth of approximately 0.6–0.75 times and 0.65–0.75 times the pile length for the hybrid foundation and the monopile respectively. The increasing loading eccentricities can lead to increasing moment bearing capacity, increasing initial stiffness and upward movement of the rotation center of the two foundations, while decreasing load sharing ratio of the single pile in the hybrid foundation. Three scenarios are considered in investigating the dynamic loading behavior of the hybrid foundation. Dynamic response results reveal that addition of the bucket to the foundation can restrain the rotation and lateral displacement effectively. The superiority of the hybrid foundation is more obvious under the combined wave and current loading.     

A Hybrid Heuristics for Irregular Flight Recovery

Adverse weather conditions, congestion at airports, and mechanical failures often disrupt regular flight schedules. The irregular flight recovery problem aims to recover these schedules through reassignments of flights and cancellations. In this article, we develop the classic resource assignment model for the irregular flight recovery problem, and a new hybrid heuristic procedure based on greedy random adaptive search procedure (GRASP) and simulated annealing algorithm is presented to solve this problem. As compared with the original GRASP method, the proposed algorithm demonstrates quite a high global optimization capability. Computational experiments on large-scale problems show that the proposed procedure is able to generate feasible revised flight schedules of good quality in less than five seconds.