Geometric design safety estimation based on tire–road side friction

A closed-loop drive–vehicle–road–environment system (DVRES) model was established using Adams/Car and Matlab/Simulink. Dynamic responses of lateral tire forces based on tire–road side friction and road geometric characteristics are used to investigate vehicle side slip for geometric design safety estimation. The root mean square, the maximum values of lateral tire forces, comfort limit on curves and vehicle trajectories are used to quantify the safety margin of side friction. The simulation results show that the safety margins of lateral tire forces for radius, operating speed and superelevation rate were 18.2%, 19.3% and 17.6%, respectively, to guarantee good vehicle lateral reliability and ride comfort, while lower speeds are optimal in wet and slippery roads. Finally, a case study was conducted to illustrate the analysis of road design safety, and on-site experiment testing further validated the accuracy and reliability of the closed-loop DVRES model.     

Tyre/road noise damping characteristics using nomographs and fundamental vibroacoustical relationships

Several studies have successfully developed laboratory and field measurement techniques to estimate tyre/road noise damping characteristics. However, laboratory–field noise correlations of pavement types in the form of nomographs is essential to cognize the pavements’ acoustical properties from a practical perspective. A toolkit that readily provides field tyre/road noise intensity of different pavement materials is needed. Thus, the main objective of this study was to develop nomographs with relationships for tyre/road noise versus pavement materials’ viscoelastic–vibroacoustical properties. Isothermal and isochronal nomographs of phase angle–tyre/road noise as toolkits were developed based upon well-established phase angle and noise intensities typical of mixtures, making the nomograph correlations very authentic, realistic, and novel along with benefit to predict tyre/road noise at any desired temperature and traffic speed (or frequency) combination. This study is envisaged to benefit in the discernment of road materials’ damping capabilities from vibroacoustical and field noise–viscoelastic relation aspects.     

RTK演算方法和厘米级卫星导航接收机

论述C/A码民用厘米级全球卫星导航接收机RTK的演算方法及非RTK接收机存在的问题,提出利用GLONASS系统与GPS系统有益的不同特性及不同的跟踪方法与GPS的有机结合,互相支持,以便使用RTK的演算方法使得厘米级定位精度的民用接收机成为现实,提高全球卫星导航系统的完善性,可靠性和定位精度。     

路面随机激励下的汽车振动仿真分析

基于某车参数建立汽车5自由度线性振动模型,模型中引入了后轮滞后路面随机激励,采用MMATLAB/SIMULINK对整车振动进行仿真模拟,将前后悬架刚度改进前后的车身和座椅处的加速度、悬架动挠度及车轮动位移4项指标进行对比分析,进而对前后悬架刚度进行优化,从而改善车辆平顺性和乘坐舒适性,可为车辆平顺性设计提供参考。     

双相化处理工艺对冷拔双相钢丝组织和性能的影响

研究了08Mn2Si钢不同工艺处理后双相组织的形态及冷拔中组织与性能的变化,结果得到:950℃预淬火后再经临界区加热淬火时可以得到细小均匀的纤维状双相组枳,这种组织在冷拔中转变为很细的平行于拔丝方向的纤维状组织,且具有最好的强度和韧性。     

抑制异步牵引电机启动峰值电流的控制策略研究

针对直接转矩控制(Direct Torque Control,简称DTC)模式下异步牵引电动机启动峰值电流过大的问题,提出了一种抑制异步牵引电机启动峰值电流的转矩和磁链同步控制策略。根据两相静止αβ坐标系下异步电机的数学模型,利用Matlab/Simulink软件包中的S函数模块和基本模块,构建出交流异步电动机直接转矩控制系统的仿真模型,对其在转矩和磁链不同控制策略下的启动过程进行了动态仿真。仿真结果与目前牵引电机运行的数据接近,证明了该仿真模型的合理性和有效性。这表明,采用转矩和磁链同步控制策略至少可以降低2/3的启动峰值电流。     

微机控制的船用发电机继电保护实验装置

由于微机控制的继电保护与常规保护比较起来有许多优点,因此微机控制的船用发电机继电保护实验装置有其取代原有实验装置的必要性。本文就微机控制的船用发电机继电保护实验装置的硬件结构、软件算法和软件抗干扰技术进行了探讨。     

船舶舵鳍联合减摇模糊变结构控制研究

分析了船舶运动的非线性模型,根据实际情况进行假设,得到了船舶舵鳍联合减摇控制系统的状态方程,把非线性船舶舵鳍联合控制模型转化为可控正则型;将船舶运动模型看作是由横摇、艏摇、横荡3个子系统构成的大系统,进行了舵鳍联合控制,设计了舵鳍联合控制器和分散非线性变结构控制器,为了改善控制的品质,又进一步提出了模糊趋近律变结构控制的方法,最后针对减摇控制器进行了MATLAB仿真研究。仿真结果表明:舵鳍联合控制器能够很好的抑制船舶的横摇和艏摇,并能尽可能的减小横荡。     

基于GIS/GPS、移动通信技术的船舶调度、监控系统

随着河道及海岸资源开发的不断深入，船舶参与施工作业的数量、频度以及复杂程度都在不断加大。针对目前存在的船舶多、作业分散、交叉施工频繁等现状，本文提出了一个综合运用地理信息系统(GIS)、全球卫星定位系统(GPS)以及移动通信技术等现代科技的船舶调度、监控系统，以对船舶实施高效、系统的管理。     

TDCS/CTC中心网络安全防护系统的补强方案

针对目前铁路局TDCS/CTC中心网络安全设备存在的问题,按现行技术标准要求提出补强方案,并阐述了方案的思路、结构、取得的效果以及技术特点。