Estimation of Road Friction Coefficient in Different Road Conditions Based on Vehicle Braking Dynamics

The accurate estimation of road friction coefficient in the active safety control system has become increasingly prominent. Most previous studies on road friction estimation have only used vehicle longitudinal or lateral dynamics and often ignored the load transfer, which tends to cause inaccurate of the actual road friction coefficient. A novel method considering load transfer of front and rear axles is proposed to estimate road friction coefficient based on braking dynamic model of two-wheeled vehicle. Sliding mode control technique is used to build the ideal braking torque controller, which control target is to control the actual wheel slip ratio of front and rear wheels tracking the ideal wheel slip ratio. In order to eliminate the chattering problem of the sliding mode controller, integral switching surface is used to design the sliding mode surface. A second order linear extended state observer is designed to observe road friction coefficient based on wheel speed and braking torque of front and rear wheels.The proposed road friction coefficient estimation schemes are evaluated by simulation in ADAMS/Car. The results show that the estimated values can well agree with the actual values in different road conditions. The observer can estimate road friction coefficient exactly in real-time andresist external disturbance. The proposed research provides a novel method to estimate road friction coefficient with strong robustness and more accurate.     

Influence Analysis of Machining and Installation Errors on the Radial Stiffness of a Non-Pneumatic Mechanical Elastic Wheel

Machining and installation errors are unavoidable in mechanical structures. However, the effect of errors on radial stiffness of the mechanical elastic wheel(ME-Wheel) is not considered in previous studies. To this end, the interval mathematical model and interval finite element model of the ME-Wheel were both established and compared with bench test results. The intercomparison of the influence of the machining and installation errors on the ME-Wheel radial stiffness revealed good consistency among the interval mathematical analysis, interval finite element simulation,and bench test results. Within the interval range of the ME-Wheel machining and installation errors, parametric analysis of the combined elastic rings was performed at different initial radial rigidity values. The results showed that the initial radial stiffness of the flexible tire body significantly influenced the ME-Wheel radial stiffness, and the inverse relationship between the hinge unit length or suspension hub and the radial stiffness was nonlinear. The radial stiffness of the ME-Wheel is predicted by using the interval algorithm for the first time, and the regularity of the radial stiffness between the error and the load on the ME-Wheel is studied, which will lay the foundation for the exact study of the ME-Wheel dynamic characteristics in the future.     

二维不规则形状自动排料算法的研究与实现

针对二维不规则形状自动排料问题,给出了解决自动排料的求解思路,并对自动排料的主要算法作出了研究和改进,以便更好地提高算法效率及可靠性。     

无机氯化物熔盐在乏燃料干法后 处理中的应用进展

综述了无机氯化物熔盐在乏燃料后处理中的应用进展,主要介绍了LiCl-KCl熔盐在金属乏燃料中的电解精炼和熔剂萃取、LiCl-Li2O在金属氧化物或混合金属氧化物（MOX）乏燃料中的电化学还原及NaCl-2CsCl在氧化物乏燃料电化学沉积中的应用进展。展望了中国无机氯化物熔盐在干法后处理中的应用前景及发展方向。     

交互式遗传算法的机器代替用户方法

如何让无疲劳的计算机代替易疲劳的用户是交互式遗传算法研究的一个重要内容.本文首先研究了机器代替用户的3个基本内容,即,机器代替用户扮演环境角色,对个体进行评价;机器采样和代替用户的时机是进入偏好稳定阶段;机器寻优结果由样本和代替用户策略决定.其次,给出基于基因意义单元"适应值"估计的个体适应值估计方法.最后,通过比较实验验证了本文方法的有效性.     

中国特色社会主义理论与实践 --浅析国有企业的改革

本文从当前国内外的形势出发,分析了构建和谐社会进行国企改革的必要性、紧迫性,阐述了国有企业改革的目标,及国有企业改革的种种举措。最后就国有企业在改革的过程中出现的众所周知的大量工人下岗的社会问题提出了一些看法。     

一个有效的多边形裁剪算法

多边形裁剪与线剪裁相比具有更广泛的实用意义,因此它是目前裁剪研究的主要课题.提出了一个多边形裁剪多边形的有效算法.其中的多边形都可以是一般多边形,既可以是凹多边形,也可以是有内孔的多边形.该算法不仅可以求多边形的"交"(多边形裁剪),而且可以求多边形的"并"和"差".它是以所提出的一系列新方法和新技术为基础而形成的.首先,该算法使用单线性链表数据结构,与其他使用双链表或树结构的算法相比,具有占用空间少及处理速度快的特点;其次,找到了两个多边形之间进、出点之间的关系.再通过合理的数据结构处理,减少了算法对多边形链表的遍历次数,而且允许多边形既可以按顺时针方向也可以按逆时针方向输入.最后,判断和计算交点是裁剪算法的主要工作.提出了一个具有最少计算量的交点判断和计算方法,进一步加快了算法的运行速度.与其他同类算法进行了比较,结果表明,新算法具有最简单的结构和最快的执行速度.