高速列车横向半主动悬挂系统建模研究及分析

半主动悬挂控制是提高高速列车横向平稳性有效的方法。然而，车辆动力学模型的复杂性。用复杂模型设计出的控制器也是复杂的，且需要多个传感器对多个物理量进行检测，使其很难在实际车辆中应用。针对这一问题，提出一种有利于控制算法设计，又能反映车辆横向振动主要特点的3自由度简化模型和利于控制算法性能研究仿真的17自由度模型，用3自由度模型设计自适应预测控制算法，用17自由度模型进行仿真验证，有效解决了模型与控制的矛盾问题。     

超临界CO2循环冷端温度优化研究

超临界CO₂循环冷端排出的热量温度较高,优化冷端温度对于提高循环的效率有重要作用。为了获得最佳的全年平均效率,有必要引入人工制冷,使超临界CO₂循环运行在更优化的冷端温度下。针对550℃/20 MPa参数的分流再压缩方式的超临界CO₂循环,通过热力学方法,分析了自然冷却和人工制冷组合条件下,冷端温度为5~35℃的不同工况下全年平均循环效率,并对冷端温度优化方法的适用性和经济性进行了研究。选取优化的冷端温度,将自然冷却和人工制冷相结合,可提高机组的全年平均效率。对于我国北方地区,冷端温度优化方法有较佳的适用性。引入人工制冷导致机组设备投资增加,但是机组运行效率的提高带来更多的发电收入,并在机组全寿期产生可观的收入增量。     

Effect of a scratch on curved rail on initiation and evolution of rail corrugation

The effect of a scratch formed on the running surface of a curved rail, due to the slide of a locomotive wheel, on the formation and evolution of rail corrugation is investigated in detail with numerical methods when a wheelset is steadily and repeatedly curving. In the calculation we consider a combination of Kalker’s rolling contact theory with non-Hertzian to be modified, a linear frictional work model and a vertical dynamics model of railway vehicle coupled with a curved track. Also the influence of different speeds of wheelset curving through the scratch on the development of the corrugation is taken into account. The numerical results indicate that a scratch causes strong contact vibration between the wheel and rail, and initiation and development of rail corrugation under the condition of steady creepage occurring between the wheel and curved rail. The wave-length of the corrugation depends on the speed of wheelset curving and the natural frequencies of the track.     

基于虚拟同步电机控制的微电网稳定性分析

随着微电网中电力电子器件的大量接入,多电源与负荷的动态特性相互耦合,使得微电网系统中稳定分析问题成为研究热点。针对基于虚拟同步电机控制的微电网系统,提出了一种含多分布式电源的系统非线性状态空间建模方法。建立了含分布式电源、线路和负荷的微电网统一状态空间方程。基于所建立的状态空间方程,运用特征根分析法研究了影响微电网系统稳定性的因素。并利用分岔理论研究了虚拟同步电机控制关键参数和系统拓扑结构参数对系统稳定性的影响。在PSCAD/ETMDC仿真平台搭建了基于虚拟同步电机控制的微电网模型,验证了所提方法的正确性和有效性。     

Effect of passenger car curving on rail corrugation at a curved track

The paper presents a corrugation calculation model, which considers Kalker's non-Hertzian rolling contact theory to be modified, a material wear model and a vertical and lateral coupling dynamics of a half passenger car and a curved track. The dynamics characters of the curved track model in frequency domain were investigated by the commercial finite element code ANSYS, and some results concerning rail corrugation are presented in this paper. During a passenger car passing a curved track the dynamical performance of the vehicle and track and the initiation and growth of the curved rail corrugation are analyzed with the present corrugation calculation model. In the numerical calculation, two track states are investigated. One is that the track does not have any congenital defect except for the discrete rail support by sleepers. The other is that the track has a lateral dent on the gauge corner of the high rail. The rail corrugations analyzed are attributed to the material wear mechanism. The numerical results obtained indicate that (1) a high passing frequency corrugation initiates on the smooth running surface of the curved rail during the first passing of the passenger car through the curved track without defects; (2) the initial corrugation develops quickly and its passing frequencies change with an increase of passenger car passage; (3) the interaction of the leading wheelset of the bogie and the curved rails causes more severe corrugation and wear on the rail running surface than that of the trailing wheelset of the same bogie; (4) discrete rail support by sleepers is the congenital defect leading to rail corrugation formation.     

Comparative study on wheel–rail dynamic interactions of side-frame cross-bracing bogie and sub-frame radial bogie

Railway Engineering Science - Improving freight axle load is the most effective method to improve railway freight capability; based on the imported technologies of railway freight bogie, the...     

基于漏洞扫描的入侵检测规则屏蔽方法研究

网络入侵检测系统的规则数在不断地增加,规则匹配的过程越来越复杂.在高速网络的环境下,NIDS(Network Intrusion Detection System)难以适应,产生漏检.将漏洞扫描与入侵检测进行融合,通过对保护对象扫描,找出存在的漏洞,根据漏洞信息将无用的规则屏蔽.实验结果表明,可以大量减少无用的检测规则;同时可以减少相应的警报信息.提高了检测效率、降低丢包率.     

一种基于DGS和EBG混合结构的毫米波滤波器设计

设计了一款可应用于毫米波频段（22.5～29.5 GHz）的小型化、高性能带通滤波器。首先利用羊角型DGS结构的谐振特性,在基片集成波导（Substrate integrated waveguide,SIW）的高通通带内产生阻带和低通特性;之后在滤波器输入微带线上耦合U型电磁带隙结构（Electromagnetic band gap,EBG）,利用该结构产生的两传输零点之间的带宽可以调整的特性,来保证滤波器通带带宽及提供高带外抑制;最后利用电磁仿真软件HFSS 13.0对滤波器进行仿真与优化。实测结果表明,该滤波器整体尺寸为10 mm×5 mm,中心频率为26 GHz,3 dB截止频率分别为22.1 GHz和29.3 GHz,带宽为7.2 GHz,相对带宽达到了28%,滤波器的插入损耗为1 dB,回波损耗优于15 dB,上、下边带带外抑制均优于25 dB,可应用于毫米波频段无线通信系统中。     

QY2智能调压调速控制器在天车起升系统的应用

介绍QY2智能起重机调压调速控制器在天车起升系统中的应用的情况.应用该控制器,系统响应快、起升平稳,解决了溜钩现象,确保了磁盘吊的安全、可靠、节能运行.     

冬期混凝土工程无覆盖施工方法初探

从负温防冻剂砼的冻结实质出发,探讨了华北地区砼工程在冬期采用无覆盖法施工的可行性。试验表明,该方法可在最低气温为-15℃时进行砼工程施工。