Luster Polish Strengthening Treatment for Raceway Surface of Aeroengine Bearings

A new surface strengthening technology, luster polish strengthening treatment, was proposed to treat the raceway surface of aeroengine bearings (9Cr18Mo) with the centrifugal strengthening machine exclusively designed for luster polish strengthening treatment. The experimental results showed that luster polish strengthening treatment produced a compressive residual stress layer with a depth of over 80 μm below the surface of the bearing raceway, and thus effectively removed the metamorphic layer in the raceway surface. After luster polish strengthening treatment, the average surface hardness of the aeroengine bearing raceway was increased from 61.02 HRC to 63.01 HRC, the surface roughness was reduced from 0.06 μm to 0.03 μm, and the contact fatigue life of the aeroengine bearings was improved by about 90%, with the dispersion of fatigue life being reduced remarkably. Theoretical calculation result agrees with that obtained by experiment.     

货车典型结构有限元多媒体示范库研制

齐车集团公司与大连铁道学院机械工程研究所联合研制开发了货车典型结构有限元多媒体示范库。该示范库主要由三部分组成：支持工厂产品设计的有限元基础知识;工厂典型产品有限元建模的关键技术及成功经验;工厂典型产品有限元分析计算实例。这些实例不仅涉及到静力分析、模态分析、动力响应,还涉及到弹塑分析、接触分析、热分析、疲劳分析乃至优化设计。该示范库以图声并茂的多媒体形式开发,并可在ＩＥ浏览器上阅读与下载。它将     

解析铁道行业标准《机车车辆用材料阻燃技术要求》

介绍TB/T 3138—2018《机车车辆用材料阻燃技术要求》的修订背景、修订原则,重点分析取样要求、保温材料、通用橡胶材料、烟密度试验和45°角燃烧试验等主要修订内容。根据我国机车车辆防火标准体系规划,提出TB/T 3138—2018标准实施建议,以便标准使用者更好地理解和实施TB/T 3138—2018。     

多轴车桥耦合振动模型的Fourier级数求解方法分析

文章以某高速公路40m简支T梁为研究对象,基于结构动力学原理推导了多轴车桥耦合振动系统的系统振动微分方程,并求解出微分方程时变激振力的Fourier级数表达式,同时基于模态叠加法得出结构动力响应的解析表达式,对该简支T梁在不同过桥车速、不同车辆车轴布置以及不同车辆车轴超重情况下的结构动力响应进行参数分析。     

Rolling horizon stochastic optimal control strategy for ACC and CACC under uncertainty

This paper presents a rolling horizon stochastic optimal control strategy for both Adaptive Cruise Control and Cooperative Adaptive Cruise Control under uncertainty based on the constant time gap policy. Specifically, uncertainties that can arise in vehicle control systems and vehicle sensor measurements are represented as normally-distributed disturbances to state and measurement equations in a state-space formulation. Then, acceleration sequence of a controlled vehicle is determined by optimizing an objective function that captures control efficiency and driving comfort over a predictive horizon, constrained by bounded acceleration/deceleration and collision protection. The optimization problem is formulated as a linearly constrained linear quadratic Gaussian problem and solved using a separation principle, Lagrangian relaxation, and Kalman filter. A sensitivity analysis and a scenario-based analysis via simulations demonstrate that the proposed control strategy can generate smoother vehicle control and perform better than a deterministic feedback controller, particularly under small system disturbances and large measurement disturbances.     

Dynamic green bike repositioning problem – A hybrid rolling horizon artificial bee colony algorithm approach

This paper introduces a new dynamic green bike repositioning problem (DGBRP) that simultaneously minimizes the total unmet demand of the bike-sharing system and the fuel and CO₂ emission cost of the repositioning vehicle over an operational period. The problem determines the route and the number of bikes loaded and unloaded at each visited node over a multi-period operational horizon during which the cycling demand at each node varies from time to time. To handle the dynamic nature of the problem, this study adopts a rolling horizon approach to break down the proposed problem into a set of stages, in which a static bike repositioning sub-problem is solved in each stage. An enhanced artificial bee colony (EABC) algorithm and a route truncation heuristic are jointly used to optimize the route design in each stage, and the loading and unloading heuristic is used to tackle the loading and unloading sub-problem along the route in a given stage. Numerical results show that the EABC algorithm outperforms Genetic Algorithm in solving the routing sub-problem. Computation experiments are performed to illustrate the effect of the stage duration on the two objective values, and the results show that longer stage duration leads to higher total unmet demand and total fuel and CO₂ emission cost. Numerical studies are also performed to illustrate the effects of the weight and the loading and unloading times on the two objective values and the tradeoff between the two objectives.     

对欧洲标准油压减振器测试规定的理解

根据对欧洲标准对测试机车车辆油压减振器的规定的理解,调查我国现有的减振器测试现状与检测各种试验台正弦激振精度后,找出差距,提出减振器测试中需试验台具备自测驱动精度、多点测试的发展目标。     

机车车辆油压减振器理论和实践上的现状与问题

围绕机车车辆油压减振器的生产与使用中漏油、线性阻尼系数、多点测试、速度点概念及发展阶段性5个方面,从理论与实践结合的层面上,理性看待现状,找出问题,以利发展。     

改进的灰度预测在列车轮径校正中的研究

列车测速定位是列控系统中的三大关键技术之一,精确的列车定位将会提高列车运行控制的安全性,缩短列车追踪间隔和提高行车效率。针对目前地铁中主流的脉冲速度传感器和应答器的组合定位技术中存在的轮径损耗问题,提出将改进的灰度预测算法应用于轮径校正中。根据列车通过定位应答器推算出的前面若干组列车轮径值,滚动预测列车下一走行区间定位计算中的轮径值,以此提高列车的定位精度,具有一定的实践意义。     

纵浪上船舶的动稳性研究

在纵浪上航行的船舶，当升沉（或纵摇）固有频率约为横摇固有频率的2倍时将发生参数激励主共振。本文考虑升沉对横摇的耦合作用，建立了非线性参数激励横摇运动方程。用多尺度方法对方程进行求解，用Floquet理论和分岔理论对定常解进行稳性分析，获得了参数激励主共振下的不稳定域和可以导致船舶倾覆的多数区域，为船舶的动稳性研究提供了一种新的方法。与数值结果的比较验证了本文的结论。