斜滑断层对埋地天然气管道力学性能影响

为研究斜滑断层作用下埋地天然气管道受力性能和影响因素,采用有限元软件ADINA进行数值模拟,建立三维管土相互作用非线性有限元模型.在该模型的基础上,分析了断层错动量、管道埋深、管径、内压以及不同管材对管道受力与变形的影响.研究结果表明:断层错动下,钢质管道最大受力与变形位置位于断层两侧,管道所受最大拉压应变相近;管道应...     

Quasi-steady-state linearisation of the racing vehicle acceleration envelope: a limited slip differential example

In the motorsport environment, passive limited slip differentials are a well-established means of improving the traction limitation imposed by the open differential. Torque sensing types are highly adjustable, and can alter both the stability and agility of the vehicle in the various cornering phases of a typical manoeuvre. In this paper, an adjustable clutch plate or ‘Salisbury’ differential model is presented, which can significantly alter its torque bias characteristics through adjustments in the drive/coast ramp angle, the number of friction faces and preload. To allow robust evaluation of differential parameter changes on ultimate vehicle performance and handling balance, a unified acceleration or ‘GG’ diagram framework is then described. This builds on traditional GG diagram approaches, by using nonlinear constrained optimisation to define both the vehicle acceleration limits and a ‘feasibility’ region within the performance envelope. By linearising a seven degrees of freedom vehicle model at multiple operating points, eigenvalue and yaw rate response analysis is then used to establish contours of stability and agility throughout the GG envelope. This brings new insights into the way in which handling balance changes below and up to the vehicle's acceleration limits.     

Vehicle dynamics control of an electric-all-wheel-drive hybrid electric vehicle using tyre force optimisation and allocation

ABSTRACT

Hybrid Electric Vehicles (HEV) offer improved fuel efficiency compared to conventional vehicles at the expense of adding complexity and at times, reduced total power. As a result, HEV generally lack the dynamic performance that customers enjoy. To address this issue, the paper presents a HEV with electric All-Wheel-Drive capabilities via the use of torque vectoring electric rear axle drive (TVeRAD) to power the rear axle. The addition of TVeRAD to a front wheel drive HEV improves the total power output. To improve the handling characteristics of the vehicle, the TVeRAD provides torque vectoring at the rear axle. A bond graph model of the drivetrain is developed and used in co-simulation with CarSim. The paper proposes a control system which utilises control allocation to optimise tyre forces. The proposed control system is tested in the simulation environment with a high fidelity CarSim vehicle model. Simulation results show the control system is able to maximise vehicle longitudinal performance while avoiding tyre saturation on low mu surfaces. More importantly, the control system is able to track the desired yaw moment request on a high speed double lane change manoeuvre through the use of the TVeRAD to improve the handling characteristic of the vehicle.     

醇胺与羧酸阻锈剂分子的构效评估与机理分析

钢筋阻锈剂是一种高性价比的钢筋防腐材料，在桥梁钢筋混凝土结构中应用广泛。有机阻锈剂的阻锈效率主要取决于其分子结构，然而受仪器设备分辨率所限，目前的相关研究多集中于宏观尺度的电化学响应分析，较少涉及微纳尺度的阻锈机理分析。因此，基于分子动力学技术，分别建立了阻锈剂与钢筋钝化膜的纳观尺度模型，模拟了醇胺类、羧酸类阻锈剂分子与钢筋钝化膜间的界面交互作用，揭示了原子尺度上的阻锈机理。基于阻锈剂-钝化膜分子动力学模型对其阻锈响应规律进行分析，确定2种有机分子均可有效阻碍氯离子在钢筋钝化膜表面的吸附和点蚀，其中羧酸类阻锈剂的阻锈效率更佳（75.8%）。通过深入探究2种阻锈剂与钢筋钝化膜基体吸附差异，研究发现：高极性的羧基官能团可与钢筋钝化膜表面的羟基发生强烈的静电吸引作用，使得羧酸类分子稳定地吸附在钝化膜表面，氯离子的吸附位点被大量占据，因而阻锈效率较高；而醇胺类分子由于官能团极性较弱，在界面上的吸附作用不显著；同时，分子模拟证明，阻锈剂中的极性官能团还能直接吸引氯离子，这一机制同样抑制了氯离子在钢筋表面的吸附和破坏；此外，电化学试验的结果与分子模拟一致，这表明分子模拟技术可在有机阻锈剂的分子设计与评估中发挥重要作用，继而为钢筋混凝土结构的耐久性设计提供科学依据与技术手段。     

Global force potential of over-actuated vehicles

This paper formulates force constraints of over-actuated road vehicles. In particular, focus is put on different vehicle configurations provided with electrical drivelines. It is demonstrated that a number of vehicles possesses non-convex tyre and actuator constraints, which have an impact on the way in which the actuators are to be used. By mapping the actuator forces to a space on a global level, the potential of the vehicle motion is investigated for the vehicles studied. It is concluded that vehicles with individual drive, compared with individual brakes only, have a great potential to yaw motion even under strong lateral acceleration.     

高性能混凝土配合比设计方法研究

结合重庆石板坡长江大桥复线桥高性能混凝土应用研究,应用数值分析方法回归得到了高性能混凝土28 d立方体抗压强度与胶凝材料比例、水泥强度、胶水比的多元线性关系,为高性能混凝土配合设计提供了参数计算的依据。     

基于人车交互行为模型的上下客行为识别

上下客行为是常见的人车交互交通行为，但随意地在路边或者禁停区域上下客，不但容易干扰道路交通秩序，还可能造成人员伤亡的恶性交通安全事故，需要及时检出以便疏导管理。受益于智慧灯杆的开发和部署，全路段的上下客行为检测成为可能。设计了一种基于智慧灯杆监控视频的人车交互行为模型HVIB（Human-Vehicle Interaction Behavior）及上下客行为识别方法，实现路边停车和上下客行为的检测。人车交互行为模型HVIB由车辆运动状态检测模块和人车关系检测模块组成。在车辆运动状态检测模块中，利用YOLOv4（You Only Look Once，Version 4）目标检测模型和SORT（Simple Online and Realtime Tracking）跟踪算法输出高置信度目标信息，并抽取车辆时空位置特征表达。在人车关系检测模块中，结合人与车辆的空间位置变化和相对运动方向，形成人车关系的时空特征表达。通过计算视频中人车时空位置特征，基于车辆运动状态判别函数和人车关系判别函数输出车辆运动状态和人车关系类别，并依据不同人车交互行为的定义，可以实现上下客行为识别。使用真实城市交通场景视频数据，对多种天气条件（晴天、阴天、雨天）下的不同人车行为进行了识别试验。试验结果表明：所提出的方法可以全天候工作，其中在白天多种天气条件下，停车和上下客行为的检测准确率能达到90%和87%以上，夜晚正常天气条件下分别为82.5%和77.5%；同时，检测速度在每秒30帧以上，满足实际应用的实时性要求。     

A novel semi-empirical tyre model for combined slips

A new tyre-force model for simultaneous braking and cornering is presented, which is based on combining existing empirical models for pure braking and cornering with brush-model tyre mechanics. The aim is to offer an easy-to-use, accurate model for vehicle-handling simulations. On a working tyre the contact patch between the tyre and the road is, in general, divided into an adhesion region where the rubber is gripping the road and a sliding region where the rubber slides on the road surface. The total force generated by the tyre is then composed of components from these two regions. The brush model describes this in a mechanical framework. The proposed model is based on a new method to extract adhesion and sliding forces from empirical pure-slip tyre models. These forces are then scaled to account for the combined-slip condition. The combined-slip self-aligning torque is also described. A particular feature of the model is the inclusion of velocity dependence, even if this is not explicitly present in the empirical pure-slip model. The approach is quite different from most previous combined-slip models, in that it is based on a rather detailed mechanical model in combination with empirical pure-slip models. The model is computationally sound and efficient and does not rely on any additional parameters that depend on combined-slip data for calibration. It can be used in combination with virtually any empirical pure-slip model and in this work the Magic Formula is used in examples. Results show good correspondence with experimental data.     

A semi-empirical dynamic tire model for combined-slip forces

This article presents a semi-empirical combined-slip tire model including transient behavior. It is assumed that the transient behavior is a result from the dynamic deformation of the tire carcass and that the interaction between the lateral and longitudinal slip, and forces can be explained by the deformation of the rubber treads. The deformation of the tire carcass makes the tread slip deviate from the wheel-rim motion in a way that may be described by differential equations. A method based on brush-model tire mechanics is used to construct the combined-slip forces as nonlinear scalings of corresponding pure-slip forces.     

浅谈公路挖孔抗滑桩与普通挖孔桩施工区别

在高速公路中 ,挖孔抗滑桩是高边坡防护、滑坡治理普遍采用的形式 ,但它在施工上却与普通挖孔桩存在根本性的区别。本文不但从结构受力、施工环境上 ,还从施工技术、工艺上阐述了与普通挖孔桩的区别 ,可供有关工程技术人员参考。