Centrifugal Pendulum Vibration Absorber (CPVA for short) is used to absorb torsional vibrations caused by the shifting motion of the engine. It is increasingly used in modern powertrains. In the research of the dynamic characteristics of the CPVA, it is necessary to obtain the real motion of the pendulum to compensate the fitting performance of mathematical model. The usual method is to install an angle sensor to measure the movement of the pendulum. On the one hand, the installation of the sensor will affect its movement to a certain extent, so that the measurement results do not match the actual motion. On the other hand, the motion of the pendulum is not only the rotational motion around the rotational axis of the CPVA rotor, but also has translation relative to it. As a result, it is difficult to obtain accurate motion only by the angle sensor. We proposed a non-contact centrifugal pendulum motion measurement method. A high-speed camera is used to photograph the motion of the CPVA. For two adjacent images recording its motion, we use the ORB descriptor with rotation invariance to obtain the key points of the images. The Brute-Force Matcher(BF Mathcer) is used to match these points. Then, we calculate the rotational motion of the absorber rotor and the translation of the centrifugal pendulum relative to the rotor after peeling off the rotational motion around it. The method can obtain the motion of the centrifugal pendulum without affecting the motion of the CPVA. It is a feasible method without installation limitation of sensors to study the dynamic characteristics of the CPVA.
To analyze the car-following behavior accurately, this paper takes the drivers’ psychological factors into the consideration based on the psychological field theory. The vehicle dynamics indexes are extracted through vehicle history trajectories and the driving styles are clustered by k-means methods. After that the perception coefficient, reaction coefficient, and driving style correction coefficient are obtained and integrated into the psychological field for characterizing the drivers’ driving styles. The psychological car-following model which considers the driving styles is built based on the Full Velocity Difference (FVD) model. Finally, the model is validated under the MATLAB/Simulink environment and the result reveals that the psychological field car-following model achieves higher accuracy of characterizing car-following behavior compared with the FVD model and the interaction potential model.
发动机冷却水套内冷却液流速分布的合理性直接影响发动机气缸体、气缸头排气侧及气缸头鼻梁区的冷却.以某四缸发动机冷却水套为研究对象,基于计算流体力学方法搭建冷却水套内部冷却液流动的计算模型,研究该冷却水套冷却液流速分布特性及评估各缸流动均匀性.冷却水套原结构状态下各缸冷却液流量及流量分配比例不均匀,缸体水套排气侧上部区域流速低于1.5 m/s且存在局部流动死区,缸头水套上鼻梁区各截面流速存在明显差异,存在冷却液流速低于1.5 m/s区域,不利于排气侧及鼻梁区高温区域的冷却.基于冷却水套初始流动结果,通过调整缸头水套上鼻梁区3个通道流通面积、缸头水套排气侧添加节流缺口、缸体水套新增2缸孔和缸体水套添加导流开口的方式对冷却水套进行了结构改进,结构改进后缸体水套排气侧区域、缸头水套下鼻梁区、上鼻梁区等高温区域的冷却液流速均满足1.5 m/s的流速要求.缸头水套鼻梁区各截面流量及流量占比间差异减小,流量分配更加均匀,有利于各缸的均匀冷却.研究结果可为四缸发动机冷却水套内冷却液流速分布特性及结构改进提供仿真数据支撑和理论指导.
污水处理厂PPP项目的复杂性和多参与方使得该类项目存在众多风险,分析项目实施过程中存在的风险并进行合理分担是保证项目顺利实施的重要一环.基于动态博弈理论分析了模型涉及的风险相关参数,提出了一种考虑信息犹豫度的确定参数权重方法,建立了政府部门和社会资本方的三回合风险再分担动态博弈模型,得出了双方的风险分担比例.以某污水处理厂PPP项目为实例进行算例分析,结果表明,政府部门和社会资本方的风险承担份额与谈判成本的大小、公私双方地位不平等、信息不对称等因素具有关联;谈判成本增大,社会资本方承担的风险会加大,政府部门占据的主导地位越高,向社会资本方转移的风险份额越大,研究结果对类似项目顺利实施具有指导意义.
无信号控制场景下,行人过街过程中存在人-车冲突,分析人-车冲突的决策过程和决策影响因素对于揭示人-车冲突机理具有重要意义.基于博弈论,综合考虑延误、风险、行人紧张程度、行人等待时间、行人和车辆驾驶人风格等影响人-车博弈决策的多种因素,合理确定了支付效用函数以及支付效用初始值,并根据人-车博弈过程构建了混合策略、"行人先行""车辆先行"3类博弈模型.博弈模型描述了行人和车辆之间的决策行为过程,通过分析纳什均衡和不同情况下博弈双方收益,得到了收益区间与策略选择的关系,得出了行人和车辆在不同情况下的占优策略和策略选择情况.研究结果表明:不同风格的行人和车辆驾驶人,在不同阶段、不同行动顺序下决策收益不同,占优策略存在差异.
