车辆—轨道系统高中低频动力学模型的理论特征及其应用范围的研究

针对铁路在提速和高速发展中碰到的车辆—轨道系统的结构磨损加剧、关键部件疲劳破坏和噪声等问题,提出必须进行车辆—轨道系统高中低频范围的动力学模型研究。根据激扰的差异及其波长范围,针对车辆—轨道系统动力学在低频、中频和高频3个范围内存在问题的性质,建立符合研究要求的车辆模型、轨道模型和轮轨接触模型,并采用合理的数学方法求解。认为以车辆—轨道系统的频率特征为基础,进行完整的车辆—轨道系统动力学研究,可以有效研究车辆—轨道系统的短时动力学和长期行为之间的关系。     

Experimental study on the nonlinear pressure acting on a high-speed vessel in regular waves

It is well known that the hydrodynamic responses of a high-speed vessel traveling in regular head waves of even moderate wave height can show significant nonlinear behavior, and so linear statistical techniques become insufficient for predicting the statistics of responses in irregular waves. On the other hand, it has been shown that an approximate third-order Volterra model is applicable to handling the statistics of some nonlinear seakeeping problems, such as motions and vertical hull girder loads. In the present study, the focus is on the nonlinear behavior of the pressure responses of the hull surface, especially on the pressures acting on alternately wet and dry areas near the waterline and on the bow zone with high deadrise angles that may be subject to slight impact and water pile-up effects. To clarify the validity of applying Volterra modeling to this problem, a series of experiments in regular and irregular head waves were carried out, and approximate third-order and fifth-order Volterra models with the proposed algorithm for finding frequency response functions (FRFs) were applied as a means of validation. In the present article, the first part of the validation was performed using experimental data in regular waves. It was confirmed that the third-order Volterra model has adequate accuracy to simulate deterministically the variation of pressure responses in regular waves of different wave steepness up to a wave amplitude to wavelength ratio of 0.01 even for the highly nonlinear pressures acting on the above-mentioned areas of the hull surface.     

杭州湾大桥北航道桥结构优化研究

应用三维空间有限元模型,进行斜拉桥结构优化设计。利用有限元法进行结构分析,求出优化所需的状态变量,挠度、应力和频率。综合考虑设计变量、状态变量和目标函数的联系,应用混合罚函数建立优化模型。运用一阶优化计算方法和引入灵敏度分析进行算法优化,使结构在应力、变形和频率等约束条件下达到最小造价。以通用有限元软件ANSYS作为平台,编制相应程序,综合考虑斜拉桥结构静力性能和动力性能,用两种不同方案对杭州湾大桥北航道桥主桥进行结构优化设计,使全桥造价分别降低9 1%和5 5%。     

基于GPRS的振弦式传感器测频系统

针对传统桥粱振动频率测量系统存在数据采集实时性差的缺点，提出基于GPRS无线网络的数据采集方法。以Atmega128单片机为现场数据采集端的MCU，并以MC35为GPRS Modem来实现与互联网接入，将GPRS无线技术引入桥梁安全检测测频系统，非常适用于要求实时性的、大数据量传送的远程数据监控系统应用场合。     

轨道电路多音调频信号的数字解调方法

针对新型数字编码轨道电路传输的窄带多音调频信号,提出利用FIR高通数字滤波器进行多音调频信号数字解调的方法。FIR高通滤波器幅频响应曲线中过渡带局部具有近似线性的特点。对采样率为10 kHz,过渡带为800 Hz至3 800 Hz的10阶FIR高通滤波器幅频响应曲线过渡带局部进行线性拟合。利用其中具有高度线性特性的部分对轨道电路窄带多音调频信号进行幅频变换,从变换结果的幅度包络中得到调制信号信息。对调制信号进行频谱分析,得到原始的列车控制编码信号。仿真结果表明,高通FIR数字滤波器鉴频特性线性度高,所需FIR滤波器阶数少,实现方法简单,在0 dB信噪比、14 dB信干比环境下能够很好地恢复原始调制信号。     

铁道客车系统的垂向减振分析

建立铁道客车垂向振动系统数学模型,计算客车系统幅频特性曲线,根据曲线峰点来确定系统自振频率,给出客车系统自振频率计算的简单近似解析方法和精确数值方法。提出客车系统各刚体振型共振速度的概念和计算公式,得出共振速度只与系统本身的自振频率和结构参数如车辆定距和转向架固定轴距有关。对客车系统在有无动力吸振器情况下的简谐和随机振动进行分析,认为采用吸振器确实能够在一定程度上抑制车体某些频率成分的振动,适当增大吸振器质量、刚度和阻尼,可以达到较好的减振效果。     

Root mean square optimization criterion for vibration behaviour of linear quarter car using analytical methods

In this paper, a linear two-degree-of-freedom quarter car model is used to derive a number of analytical formulae describing the dynamic behaviour of passively suspended vehicles running on a harmonically bumped road. The linearity of the system allows us to analytically investigate the steady-state response characteristics. We derive analytical expressions for the root mean square (RMS) of the sprung mass absolute acceleration and relative displacement. This paper demonstrates the shortcomings of existing classical optimization methods. Hence we introduce a new optimization method based on minimizing the absolute acceleration RMS with respect to the relative displacement RMS. The RMS optimization method is applied for the symbolic derivation of analytical formulae featuring the best compromise among conflicting performance indices pertaining to the vehicle suspension system, i.e., sprung mass acceleration and working space. The proposed optimization technique is utilized to find the optimal damping and stiffness curves for the main suspension. The RMS optimal values are used to create design charts for suspension parameters, which are very useful particularly in the presence of physical constraints such as a limit on relative displacement. We introduce a numerical example to illustrate the optimality of the obtained solutions.     

ZPW-2000A区段工频干扰成因分析及整治方案研究

通过典型实例,深入分析了电气化区段50Hz工作频率对ZPW-2000A信号的干扰,提出了抑制电气化区段牵引电流干扰的措施,对指导信号施工、验收、维护工作,减小电气化区段牵引电流的干扰,具有重要意义。     

无线射频识别技术在车辆识别系统中的应用研究

介绍了将无线射频识别技术应用于车辆识别系统的方案，提出了基于无限射频识别技术的车辆电子牌照概念。着重讨论基于射频技术的电子牌照及车辆识别系统的应用。并针对不同的应用场录设计程序工作流程。     

Comparing operator and users costs of light rail, heavy rail and bus rapid transit over a radial public transport network

A model to compare three alternative forms of public transport - light rail, heavy rail and bus rapid transit - is developed for an urban network with radial lines emanating from the borders to the city centre. The theoretical framework assumes an operation aimed at minimising the total cost associated with public transport service provision, which encompasses both operator and users costs. The decision variables are the number of lines (network density) and the frequency per period for each mode. This approach has no prejudices a priori in respect of whether a specified delivery scenario is aligned with existing modal reputation. Rather, we establish the conditions under which a specific transit mode should be preferred to another in terms of the operator (supply) and user (demand) side offerings. The model is applied using data from Australian cities, suggesting that in most of the scenarios analysed a high standard bus service is the most cost-effective mode, because it provides lower operator costs (infrastructure, rolling stock and operating cost), access time costs (due to a larger number of lines) and waiting time cost (due to larger frequencies of operation). A rail mode, such as light rail or heavy rail, may have a lower total cost only if it is able to run faster than bus rapid transit, and the difference in speed is enough to outweigh the bus advantage on operator cost and access and waiting times.