高速公路模糊神经网络限速控制与仿真研究

高速公路限速控制是一个非线性时变系统,难于用数学模型准确建模,提出一种模糊神经网络实现限速控制。本文阐述了网络的结构和学习算法,根据高速公路车辆群状态、路面性能、气象条件等,建立交通流速度限制模糊神经网络模型,并进行了仿真研究。仿真结果表明网络训练速度快、精度高,适合交通流限速控制的在线建模。该方法切实可行,可使交通流更加均匀、稳定,从而提高主线运行的安全和效率。     

某一级公路沥青路面破坏原因分析

某一级公路沥青路面通车不久就出现推移、凹陷、唧泥质量问题，使用寿命骤减。对该段沥青路面进行路况调查、钻芯取样试验、弯沉测定、部分原材料质量检查、高温稳定性试验，对该段沥青路面破坏的原因进行初步分析。     

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运用微观经济学方法，阐述了当前超载治理中存在的“罚-超悖论”和“重罚策略”两种主流观点。运用运输经济学相关理论修正并改进了重罚策略模型，使用该模型分析了超载执法处罚的取缔率与边际处罚对业者装载决策的影响，推导出有效执法的必要条件是保证一定的“最小期望边际处罚”，解释了车辆装载量在执法条件下的微观与宏观变化趋势。通过对超载车辆处罚设计与实际治超过程中一些约束因素的分析，解释了当前普遍依靠多执法点进行重复处罚的原因与该策略可能存在的弊端。     

国内外高速公路的发展状况

简要的介绍了国内外高速公路发展和研究的现状 ,对欧洲和美国先进的高速公路建设和管理理念进行了总结 ,并对我国高速公路的发展以及在建设和管理中存在的问题进行了分析 ,找出了与发达国家之间的差距 ,以此来更好的促进和完善我国高速公路的发展     

基于Adams与Matlab联合仿真的摆式列车动力学计算

为了研究摆式列车动力学性能,建立了摆式列车机电耦合动力学模型,并运用Adams与Matlab/Simulink联合仿真的技术进行数值计算,研究了多种工况下摆式列车的动力学性能,通过与普通车辆之间的对比表明,摆式列车具有在较小影响其动力学性能的前提下明显改善旅客乘坐舒适度,并提高列车曲线通过速度。     

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分析了辽宁省公路交通网络的基本现状，根据分形理论，利用Hausdorff维数简化算法和空间关联维数的计算方法，测算了以省内国道干线为基础的辽宁省公路交通网络的分维数和网络直通度.通过对比分析数值得出辽宁省干线公路网络的分维数比较低，网络直通度比较高的结论.并指出辽宁省公路交通网络应从提高网络直通度向提升线路等级，从而向缩短运输时间、增大运量的方向转移.     

Mal-operation Reason Analysis and Solution for Differential Voltage Protection of Shunt CapacitorsEI北大核心

Research purposes: Shunt capacitors are the important device of power system in electrified railway. The relay for shunt capacitors is equipped with over-current, harmonic over-current, difference current, differential voltage protections, etc. When HXD locomotive went through some power supply arms on Long-Hai line, mal-operation of differential voltage protection for shunt capacitors occurred frequently. According to load characteristic of AC-DC-AC locomotive and actual situation on site, the fault wave of differential voltage protection in a traction substation is analyzed, the reason of mal-operation is found, and the corresponding solution is got. Research conclusions:(1) The mal-operation reason of differential voltage protection is caused by Fourier transform which is influenced by frequency aliasing. The influence of frequency aliasing results in the amplification of differential voltage value and mal-operation of differential voltage protection. (2) By altering the sampling frequency from 20 points per period to 100 points per period, the influence of frequency aliasing on Fourier transform is eliminated. (3) There have been no longer mal-operations of differential voltage protection, ever since the revised program of protection came into use. (4) In the area of power supply system of electrified railway, this analytical method and solution have important reference value in analysis and application of electrical quantities with higher harmonics. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

The Methodology Research on the Test and Evaluation of Static Stiffness of Elastic Pads in Elastic Separated FastenerEI北大核心

Research purposes: In order to explore the reasonable test and evaluation methods of the static stiffness of the elastic pads in elastic separated fastener, the influences of various factors on the static stiffness of the elastic pads were tested and analyzed by single factor test, a reasonable static stiffness test plan for the elastic pads was proposed. Besides, the evaluation suggestions for static stiffness of rail pad and baseplate pad were analyzed in terms of the installation state of the elastic separated fastener. Research conclusions:(1) The test of the static stiffness of elastic pad should include two stages: preloading stage and formal loading stage. Firstly, the elastic pad shall be preloaded with no less than 2 times at a loading rate of 3-5 kN/s, and the preloaded maximum load shall be at least 10 kN higher than the static stiffness test load range of the elastic pad. Then, formal loading is supposed to be carried out at least 3 times with a loading rate of 1~2 kN/s, and at both ends of the load range the load should be maintained for 90 s, which could be shortened to 60 s in special case when the load is less than 100 kN. Finally, the static stiffness of the elastic pad is calculated by the average value of the three test results. (2) The evaluation methods of static stiffness of rail pad and baseplate pad are dissimilar. The static stiffness of the rail pad could be evaluated by the secant stiffness in the range of 20~70 kN, while the evaluation of static stiffness of baseplate pad should be processed in terms of the reasonable static stiffness test load range of baseplate pad determined by the installation torque of anchored bolt. (3) This research results can be applied in the test and evaluation of static stiffness of rail pad and baseplate pad in elastic separated fastener. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

Distributed and self-adaptive vehicle speed estimation in the composite braking case for four-wheel drive hybrid electric car

Considering the controllability and observability of the braking torques of the hub motor, Integrated Starter Generator (ISG), and hydraulic brake for four-wheel drive (4WD) hybrid electric cars, a distributed and self-adaptive vehicle speed estimation algorithm for different braking situations has been proposed by fully utilising the Electronic Stability Program (ESP) sensor signals and multiple powersource signals. Firstly, the simulation platform of a 4WD hybrid electric car was established, which integrates an electronic-hydraulic composited braking system model and its control strategy, a nonlinear seven degrees-of-freedom vehicle dynamics model, and the Burckhardt tyre model. Secondly, combining the braking torque signals with the ESP signals, self-adaptive unscented Kalman sub-filter and main-filter adaptable to the observation noise were, respectively, designed. Thirdly, the fusion rules for the sub-filters and master filter were proposed herein, and the estimation results were compared with the simulated value of a real vehicle speed. Finally, based on the hardware in-the-loop platform and by picking up the regenerative motor torque signals and wheel cylinder pressure signals, the proposed speed estimation algorithm was tested under the case of moderate braking on the highly adhesive road, and the case of Antilock Braking System (ABS) action on the slippery road, as well as the case of ABS action on the icy road. Test results show that the presented vehicle speed estimation algorithm has not only a high precision but also a strong adaptability in the composite braking case.     

Effects of altitude on combustion characteristic during cold start of heavy-duty diesel engine

Altitude has a significant effect on combustion of heavy-duty diesel engines, especially during cold start. An experimental study on a heavy-duty diesel engine operating at different altitudes was conducted. Tests were based on a direct injection (DI) turbocharged diesel engine with intake and exhaust pressure controlled by the plateau simulation test system to stimulate altitude conditions including 0 m, 1000 m, 2000 m, 3000 m and 4000 m. Results indicated that the compression and expansion resistance moment reduced and the speed increased during the cranking period. The peak pressure of several cycles was increased during the start-up period; however, the expansion pressure dropped more and the indicated mean effective pressure (IMEP) reduced as the altitude rose. While at an altitude of over 2000 m, the peak pressure fluctuated obviously during the start-up period. The higher the altitude was, the more the fluctuation amplitude and cycle number increased and combustion instability enhanced, which resulted the start-up period time increasing at high altitude. When the altitude rose, the cycle-to-cycle variation of the peak pressure and speed fluctuation increased during the idle, the ignition and CA50 were delayed and the combustion duration was shortened. The effect of altitude on combustion characteristics of the diesel engine was more significant during the start-up period than during its idle period.