基于自适应模糊PI的汽车直接摆力矩控制研究

针对汽车直接横摆力矩控制,论文研究了基于自适应模糊PI的控制方法。设计了基于自适应模糊PI的附加横摆力矩决策控制器和基于规则分配的制动力分配器。横摆力矩决策控制器根据汽车横摆角速度期望值和车辆状态决策出所需的附加横摆力矩,通过规则制动力分配方法进行主动差动制动实现,并采用Matlab/Simulink与CarSim联合仿真对控制方法进行仿真试验验证。结果表明:基于自适应模糊PI的横摆力矩控制方法相对于未控制能够使汽车较好地跟踪期望,有效提高汽车操纵稳定性。     

基于CAA的高速动车组气动噪声仿真研究

随着列车运行速度的提高,气动噪声在总噪声中所占的比重越来越大,降低气动噪声已成为影响高速铁路可持续发展的关键问题。在理论研究基础上,采用了混合法来研究高速动车组受电弓周围的气动噪声特性。首先,对高速列车在RANS(雷诺平均模拟)方法计算下的统计结果进行分析,研究高速列车受电弓区域的流场特征。然后,应用非线性声学求解方法(NLAS)研究近场噪声,分析了不同部位对气动噪声的贡献。最后,采用FW-H声学比拟方法来分析远场气动噪声,通过不同测试点研究了远场噪声分布特性。     

联合机动编队兵力配置冲突消解

联合机动编队兵力配置是攻防作战的前提,众多兵力同时配置产生的冲突制约编队战斗力的发挥。着眼于联合机动编队整体作战效益,对联合机动编队兵力配置中的冲突消解问题展开研究。在分析联合机动编队兵力配置冲突产生原因的基础上,确定消解冲突的原则,针对联合机动编队兵力配置中的典型冲突问题提出消解方法,为解决联合机动编队兵力配置中的冲突问题提供思路。     

横向拓宽空心板简支梁桥基础沉降次内力分析

为得到横向拓宽空心板桥基础沉降的次内力影响,本文以某一级公路扩建工程为背景,建立了三维实体有限元模型,并考虑沉降计算模式及徐变的影响,对拼宽部位结构的次内力及适宜构造进行分析探讨。基于本例计算,作者推荐空心板简支梁桥的拓宽拼接构造宽度为0.5m左右。     

浅水中低速斜航船舶水动力预报及验证与确认分析

浅水中的斜航船舶受到浅水阻塞效应和不对称流的综合影响。为预报该运动中的船舶水动力,文章采用基于定常雷诺平均纳维—斯托克斯方程的计算流体动力学方法,对浅水中做斜航运动的船舶粘性绕流场进行数值模拟。考虑低航速运动的特点,忽略航速影响下的自由面兴波,由数值计算得到水动力系数在漂角影响下的变化规律。针对计算精度问题,在数值模拟中从验证和确认角度分析和评估计算结果：通过网格收敛性分析分析数值误差与不确定度;结合试验数据考察计算模型的误差。此外,从计算区域尺度、湍流模型、边界条件、船体下沉和纵倾作用方面对模型误差的影响因素进行探讨,可为改进计算模型、提高数值模拟精度提供参考依据。     

贵港二线船闸泄水阀门体型研究*

贵港船闸是西江航运干线的咽喉,航运地位十分重要。通过建立比尺为1:15的泄水阀门非恒定流常压模型,对6种动水关门事故工况条件下贵港船闸泄水阀门3种体型的动水启闭力特性进行了系列研究,获得阀门底缘形式、阀门下游侧面板是否封闭对动水启闭力的影响规律：阀门下游侧面板不封闭将使下游河道水位的波动直接传播到阀门门井中,导致阀门启闭力反复波动;当阀门底缘朝下时,底缘斜面压力小,底缘受力主要表现为下吸力,因此对应开门过程启门力大、闭门过程闭门力小;阀门底缘朝上,底缘斜面压力大,底缘受力主要表现为上托力,因此对应开门过程启门力小、闭门过程闭门力大,采用底缘朝上型阀门时,应考虑阀门配重。     

Velocity and normal tyre force estimation for heavy trucks based on vehicle dynamic simulation considering the road slope angle

A precise estimation of vehicle velocities can be valuable for improving the performance of the vehicle dynamics control (VDC) system and this estimation relies heavily upon the accuracy of longitudinal and lateral tyre force calculation governed by the prediction of normal tyre forces. This paper presents a computational method based on the unscented Kalman filter (UKF) method to estimate both longitudinal and lateral velocities and develops a novel quasi-stationary method to predict normal tyre forces of heavy trucks on a sloping road. The vehicle dynamic model is constructed with a planar dynamic model combined with the Pacejka tyre model. The novel quasi-stationary method for predicting normal tyre forces is able to characterise the typical chassis configuration of the heavy trucks. The validation is conducted through comparing the predicted results with those simulated by the TruckSim and it has a good agreement between these results without compromising the convergence speed and stability.     

Nonlinear analysis of wind-induced vibration of high-speed railway catenary and its influence on pantograph–catenary interaction

The wind-induced vibration of the high-speed catenary and the dynamic behaviour of the pantograph–catenary under stochastic wind field are firstly analysed. The catenary model is established based on nonlinear cable and truss elements, which can fully describe the nonlinearity of each wire and the initial configuration. The model of the aerodynamic forces acting on the messenger/contact wire is deduced by considering the effect of the vertical and horizontal fluctuating winds. The vertical and horizontal fluctuating winds are simulated by employing the Davenport and Panofsky spectrums, respectively. The aerodynamic coefficients of the contact/messenger wire are calculated through computational fluid dynamics. The wind-induced vibration response of catenary is analysed with different wind speeds and angles. Its frequency-domain characteristics are discussed using Auto Regression model. Finally, a pantograph model is introduced and the contact force of the pantograph–catenary under stochastic wind is studied. The results show that both the wind speed and the attack angle exert a significant effect on the wind-induced vibration. The existence of the groove on the contact wire cross-section leads to a significant change of the aerodynamic coefficient, which affects largely the aerodynamic forces applied on the catenary wires, as well as the vibration response. The vibration frequency with high spectral power mainly concentrates on the predominant frequency of the fluctuating wind and the natural frequency of catenary. The increase in the wind speed results in a significant deterioration of the current collection. The numerical example shows that a relatively stable current collection can be ensured when the wind flows at the relatively horizontal direction.     

Simulation of longitudinal dynamics of a freight train operating through a car dumper

A heavy haul train and car dumper model was created to analyse train longitudinal dynamics during dumping. Influence of such factors as performance curve of draft gears, total free slack in couplers, operating mode of train positioner and braking of last two cars of train on the in-train forces was considered.     

双排抗滑桩在高家坪滑坡治理中的应用

抗滑桩因其良好的抗滑能力被广泛应用于滑坡治理中。针对宝成铁路109隧道改线段高家坪滑坡设置了两排抗滑桩,滑坡体前缘支挡防护措施,做好坡面排水和防水;采用FLAC3D数值模拟和传递系数法对滑坡体稳定性、滑坡推力和抗滑桩内力进行了计算和分析,说明双排抗滑桩设计合理。实践证明抗滑桩方案整治效果良好,确保了改线段铁路工程的稳定,该滑坡整治经验可供同类工程施工参考。