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211.
Yinyu Nie Fengjia Liu Jian Chang Jianjun Zhang 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2018,56(3):406-427
The finite element (FE) method is essential for simulating vehicle dynamics with fine details, especially for train crash simulations. However, factors such as the complexity of meshes and the distortion involved in a large deformation would undermine its calculation efficiency. An alternative method, the multi-body (MB) dynamics simulation provides satisfying time efficiency but limited accuracy when highly nonlinear dynamic process is involved. To maintain the advantages of both methods, this paper proposes a data-driven simulation framework for dynamics simulation of railway vehicles. This framework uses machine learning techniques to extract nonlinear features from training data generated by FE simulations so that specific mesh structures can be formulated by a surrogate element (or surrogate elements) to replace the original mechanical elements, and the dynamics simulation can be implemented by co-simulation with the surrogate element(s) embedded into a MB model. This framework consists of a series of techniques including data collection, feature extraction, training data sampling, surrogate element building, and model evaluation and selection. To verify the feasibility of this framework, we present two case studies, a vertical dynamics simulation and a longitudinal dynamics simulation, based on co-simulation with MATLAB/Simulink and Simpack, and a further comparison with a popular data-driven model (the Kriging model) is provided. The simulation result shows that using the legendre polynomial regression model in building surrogate elements can largely cut down the simulation time without sacrifice in accuracy. 相似文献
212.
Bin Yang Wu Qiang Zhan Shun Kai Zhang Xiao Kun Nie Yu Han Li Wanhua Su 《International Journal of Automotive Technology》2018,19(4):623-633
Experiments and simulations were used to investigate the effect of a range of engine operating parameters and fuel characteristics on the particle size and particle number (PN) concentration at low speed and idle speed condition. The occurrence, size, and concentration of particles were tested against a range of parameters including start of injection (SOI), common rail pressure, exhaust gas recirculation (EGR) ratio and load. The results showed that the homogeneity of the mixture had the greatest impact on particle size and number concentration. The performance of particle is different at different levels of load. The particle were of nucleation mode at idle condition, and the cold idle particles had a slightly larger diameter than those produced at hot idle. By using the diesel and under high load, at EGR ratios of less than 20 %, most particles were of nucleation mode. At EGR ratios exceeding 20 %, nucleation-mode particles were gradually replaced by accumulation-mode particles. At EGR ratios above 30 %, most particles were of the accumulation mode. Under the same load, gasoline compression ignition produced particles of smaller size and reduced particulate mass (PM). The use of gasoline extended ignition delay, as the high volatility and octane number of the fuel improved the homogeneity of the mixture. Finally, a linear relationship was found between PM and PN. The relative contribution of the different factors to the formation of nucleationor accumulation-mode particles was investigated. 相似文献
213.
对AutoCAD(ACAD)的开放式体系结构进行深入探索,利用ACAD提供的开发工具,结合板桩码头专业设计的特点,研究开发了一套多功能、实用的计算机辅助设计系统。 相似文献
214.
在中国典型城市公交循环工况下,采用车载排放测试技术,以纯柴油模式的怠速排放水平作为比较基准,对某一大型混合动力客车发动机的启动/停止(S/S)对排放特性的影响进行了研究.试验结果表明:从排放总量上看,混合动力汽车的HC、CO、NO_x、CO_2和PM的排放量都比纯柴油模式低;而混合动力模式S/S阶段的HC、CO和NO_x的排放量要比纯柴油模式怠速排放量低;但是PM排放量相反,混合动力发动机在启动和停止时都出现排放峰值;从控制PM排放量来说,该混合动力客车停机时间应长于7s. 相似文献
215.
装配SCR系统的混合动力公交车排放特征研究 总被引:1,自引:0,他引:1
利用车载测试系统,对两种类型的混合动力公交车进行了整车排放测试,研究了装备SCR系统的国Ⅳ混合动力公交车排放情况,结果表明,SCR技术的应用能一定程度上降低Nox排放量,但同时SCR技术在混合动力公交车上实际应用时存在排气温度过低、从而导致Nox转化率偏低的问题.建议采用某种技术(如排气加热系统)提高城市公交车排气温度或提高SCR的低温性能,以便提高Nox转化效率. 相似文献
216.
217.
国家交通是军事交通的重要基础和依托,国家交通运输的发展必然对军事交通运输产生影响。从二者的相互关系人手,以抓住发展机遇、强化贯彻国防要求,迎接挑战、加强交通运输动员法规制度建设,适应市场变革、及时调整改革军事运输政策,适应新变化、及时调整驻交通沿线军事代表体制为切入点,系统分析了国家交通运输改革与发展对军事交通运输发展所产生的影响,并提出了相应的对策措施。 相似文献
218.
随着城市化发展小汽车拥有量的增加,引起了城市中心区道路交通的严重拥堵,降低了出行效率.为此,北京、上海和广州等大城市通过提高公共交通服务水平,形成地铁、快速公交与较为发达的地面公交相结合的公共交通系统,吸引小汽车通勤出行者选择驻车换乘(Parking and Ride,P+R),进入城市中心区.本文结合北京市轨道交通沿线居民小汽车出行和地铁换乘,形成小汽车与轨道接运的特点,在总结北京城市轨道网特征及规模基础上,通过个体意愿调查统计,构建P+R出行方式选择模型,对地铁5号线终端站天通苑P+R驻车换乘需求进行了预测,为P+R建设和公共交通吸引能力分析提供参考. 相似文献
219.
220.
SUN Li-ping NIE Wu ZHANG Wei 《船舶与海洋工程学报》2006,5(1):1-5
1Introduction Therearethreefamiliarmethodstocalculatedynamic characteristicsofconventionalshipstructures:energy method,transfermatrixmethodandfiniteelement method.Forenergymethodanapproximatelyvibration deflectionfunctionmustbeassumed.Soitisalmostim possi… 相似文献