极限状态响应面法分析结构可靠度的研究

一般响应面方法由于逼近的是功能函数而非极限状态方程,因而精度有时不高。为克服此不足,提出一种极限状态响应面法。该方法利用位于极限状态曲面上的样本点来重构结构的极限状态方程,因而模拟出的极限状态曲面精度较高。由此提出一种算法,通过逐步修正求解得到的设计点以实现在设计点附近较高精度地逼近结构真实极限状态方程。该方法同时克服了重构极限承载力曲面方法不能适用多个荷载随机变量的缺点。数值算例表明该方法具有较高的精度,适用范围广,而且所需样本点数量少。     

高速公路车速与交通安全

从运行车速、超速行驶、速度差以及限速等与车速有关的方面分析了车速与交通安全的关系,得出了相关的结论。     

A tyre slip-based integrated chassis control of front/rear traction distribution and four-wheel independent brake from moderate driving to limit handling

This paper presents a tyre slip-based integrated chassis control of front/rear traction distribution and four-wheel braking for enhanced performance from moderate driving to limit handling. The proposed algorithm adopted hierarchical structure: supervisor – desired motion tracking controller – optimisation-based control allocation. In the supervisor, by considering transient cornering characteristics, desired vehicle motion is calculated. In the desired motion tracking controller, in order to track desired vehicle motion, virtual control input is determined in the manner of sliding mode control. In the control allocation, virtual control input is allocated to minimise cost function. The cost function consists of two major parts. First part is a slip-based tyre friction utilisation quantification, which does not need a tyre force estimation. Second part is an allocation guideline, which guides optimally allocated inputs to predefined solution. The proposed algorithm has been investigated via simulation from moderate driving to limit handling scenario. Compared to Base and direct yaw moment control system, the proposed algorithm can effectively reduce tyre dissipation energy in the moderate driving situation. Moreover, the proposed algorithm enhances limit handling performance compared to Base and direct yaw moment control system. In addition to comparison with Base and direct yaw moment control, comparison the proposed algorithm with the control algorithm based on the known tyre force information has been conducted. The results show that the performance of the proposed algorithm is similar with that of the control algorithm with the known tyre force information.     

参数化集装箱正面吊运机力矩限制方法的研究

通过对集装箱正面吊运机力矩限制数学模型的研究，提出一种新颖的参数化力矩限制方法。该方法不需关心繁杂的机器几何参数，可降低力矩限制控制系统对机械结构及有关参数的依赖程度，提高开发调试效率；可用于集装箱正面吊运机的力矩限制安全保护。     

长寿柔性基层沥青路面的极限应变

长寿柔性路面设计通常采用沥青层底极限拉应变和土基顶部极限压应变作为控制指标。现阶段极限应变指标参照室内试验结果确定，且数值相对固定。而现场路面结构层应变响应值受结构厚度、荷载、环境作用（温度及老化）等因素的影响，在服役过程中不断演化。以2条服役超过35年的柔性路面结构（屯门公路与吐露港公路）为基础，分析了不同服役阶段路面结构层在不同荷载、环境作用下的极限应变响应，探讨了柔性路面极限应变的大概范围。研究结果表明：在初始服役状态下，屯门公路高温状态下沥青层底的极限拉应变为376×10^-6，土基顶部极限压应变为562×10^-6；低温状态下上述极限应变分别降为87×10^-6，249×10^-6；吐露港公路高温状态下沥青层底、土基顶部极限应变分别为149×10^-6，324×10^-6，低温状态下上述应变分别降为50×10^-6，156×10^-6。在经过长期服役后，老化状态下2类路面沥青层底拉应变及土基顶部压应变均大幅降低。屯门公路在使用36年后，某些路段出现零星的疲劳破坏，而吐露港公路则没有发现疲劳破坏。极限应变计算结果表明，路面关键位置的应变受荷载、沥青层厚度、温度和沥青层老化状态等多因素的影响。因此，在进行长寿柔性基层路面设计中，荷载、沥青层厚度、温度及沥青层老化状态等因素都应该考虑在内。     

回转支承应用于平地机驱动桥与平衡箱联接

针对平地机后驱动桥与平衡箱联接存在零件加工和安装精度要求高、联接受力复杂、普通轴承易损坏、可靠性差等问题。提出了采用专用、特殊的轴承——回转支承联接的方法。通过适当选型并经过计算验证，该方法满足了平地机后驱动桥和平衡箱联接的强度和工作要求，且方便可行。     

Limit braking of a high-performance motorcycle

A mathematical-model-based study of the limit braking of a high-performance motorcycle and rider is described. Front and rear brakes are operable independently. A dry road and high friction are presumed, such that full braking of the front wheel would lead to an overturn or ‘stoppie’ in colloquial parlance. Effective braking needs to maintain some loading on the rear wheel. A planar but otherwise detailed system model is set up and braking strategies for front and rear are devised. Parameters of the braking control schemes are derived with the help of an optimisation process, minimising the final speed in braking from high speed over a fixed time interval. Simulation results are examined critically and the strategy is developed until efficient use of the friction available is made. The nature of optimal braking events is demonstrated. The influences of slipper-clutch torque setting and the rear-tyre target load chosen are shown.     

基于用户平衡分析的铁路旅客列车票额分配计划制定及评价方法

票额分配计划必须最大限度地满足旅客集体乘车选择行为下长途旅客的出行需求,其中的旅客集体乘车选择行为表现为基于客车开行方案的换乘网络上的用户平衡态,据此平衡态提出以直接人公里数最大为目标的票额分配计划制定方法。进而根据短途套用、票额共用和席位复用等售票策略、以及这些策略对旅客集体乘车选择行为的影响,设计基于票额分配计划的换乘网络,依据该换乘网络上的用户平衡态,提出以旅客出行费用和票额分配计划的直接人公里数两项指标组成的评价方法。通过算例展示了票额分配计划的制定过程,并对不同票额分配计划进行了评价分析。     

混合交通平衡分配方法的研究

针对我国机动车与非机动车混合行驶、相互干扰的混合交通机制，把机动车和非机动车的相互影响因素考虑到交通阻抗函数中，在此基础上，建立混合交通UE分配模型及其算法。最后，将该算法运用到云南省保山市隆阳区的局部路网中。     

解析法和Excel在液塑限试验中的应用

液塑限试验中,一般用作图法来求液塑限,但手工作图较为繁琐,且误差较大。介绍了解析法的原理并编制了相应的Excel表格,使得计算速度和准确性大为提高。