Sensitivity analysis to assess the influence of the inertial properties of railway vehicle bodies on the vehicle's dynamic behaviour

A sensitivity analysis has been performed to assess the influence of the inertial properties of railway vehicles on their dynamic behaviour. To do this, 216 dynamic simulations were performed modifying, one at a time, the masses, moments of inertia and heights of the centre of gravity of the carbody, the bogie and the wheelset. Three values were assigned to each parameter, corresponding to the percentiles 10, 50 and 90 of a data set stored in a database of railway vehicles. After processing the results of these simulations, the analysed parameters were sorted by increasing influence. It was also found which of these parameters could be estimated with a lesser degree of accuracy for future simulations without appreciably affecting the simulation results. In general terms, it was concluded that the most sensitive inertial properties are the mass and the vertical moment of inertia, and the least sensitive ones the longitudinal and lateral moments of inertia.     

长大列车动力学建模的一种新方法

提出了一种全新的列车动力学建模方法,即基于循环变量的模块化建模方法。该方法彻底解决了长大列车的建模难题,为深入研究列车系统的各类动力学问题打下了良好的基础。     

Longitudinal force distribution using quadratically constrained linear programming

In this paper, a new method is presented for the optimisation of force distribution for combined traction/braking and cornering. In order to provide a general, simple and flexible problem formulation, the optimisation is addressed as a quadratically constrained linear programming (QCLP) problem. Apart from fast numerical solutions, different driveline configurations can be included in the QCLP problem in a very straightforward fashion. The optimisation of the distribution of the individual wheel forces using the quasi-steady-state assumption is known to be useful for the study of the influence of particular driveline configurations on the combined lateral and longitudinal grip envelope of a particular vehicle–driveline configuration. The addition of the QCLP problem formulation makes another powerful tool available to the vehicle dynamics analyst to perform such studies.     

空调硬卧车内人体热舒适性研究

针对目前空调硬卧车内气流分布不均匀,不同铺位的乘客对车厢内的热舒适感差别较大这一现状,采用计算流体动力学对空调硬卧车内流场和温度场进行了数值模拟,研究了空调硬卧车内空气流动速度和温度分布规律及热舒适评价指标PMV和人体吹风感指标PD分布状况。研究结果对于改变目前车厢内上、中、下铺气流分布不均的现状,改善车厢内人体热舒适环境提供了理论依据。     

瞬态冲击下车辆动力学建模及仿真计算

车辆系统受到瞬态冲击是一种常见的工况,文章建立了瞬态冲击下车辆系统的动力学模型,采用Simulink软件对系统响应进行动态仿真计算,得出每节车在瞬态冲击下的加速度、速度、位移等动态曲线图。该仿真方法计算结果清晰,数据可靠,具有较高的工程应用价值。     

高速列车与桥上板式轨道动力学仿真分析

运用轮轨关系,建立高速列车—板式轨道—桥梁系统空间耦合动力学模型。运用列车—线路—桥梁动力学仿真通用软件TTBSIM,分析高速列车以不同速度通过桥梁时,机车车辆、板式轨道及桥梁的动力特性。结果表明,桥上板式轨道能够保证行车的安全性、舒适性和桥梁结构的安全性。     

SS7E型电力机车横向晃动问题的理论分析

基于系统工程思想，运用TTISIM动力学仿真软件，详细分析了机车在直线轨道上车体与构架横向振动位移，发现该机车在80km／h和100-130km／h速度范围之内存在较剧烈的横向振动现象。这与目前该机车在试运行过程中所发现的问题相一致。为有效地抑制机车横向异常晃动，在保持转向架结构不变的前提下，对机车悬挂参数进行了优化，并在此基础上提出了2套综合改进方案。     

200 km/h提速客车径向转向架动力学性能研究

径向转向架是改善机车车辆曲线通过性能的有效途径。简要介绍了国内外径向转向架发展现状 ,阐述了径向转向架的导向机理及基本结构模式。根据自导向径向转向架的基本原理 ,在现有的几种自导向转向架结构的基础上 ,提出了 2 0 0km/h提速客车自导向径向转向架的基本方案 ,建立了动力学仿真模型 ,利用Simpack仿真软件对其进行了动力学性能分析和计算 ,并与常规转向架进行了比较。理论分析和计算结果表明 ,提速客车采用径向转向架可有效地改善曲线通过性能和降低轮轨磨耗     

Analysis of Flux of Gas Passing Circle Lacuna

The rate of flow of the gas flowing through cirque chink often needs calculation in engineering. The characters of compressibility and thermodynamics have some effect on the gas flowing, so the analysis on the flow of gas is more complex than that of liquid. But under different conditions and different I'equirements of precision the analysis can be simplified suitably, then make the formulae given become simple subsequently. This paper analyzes various gas flux based on basic characters and motion laws of gas and the analysis is just applied in an engineering project.     

Carbon and nutrient dynamics in a hypertrophic lagoon in southwestern Taiwan

Dissolved and particulate phases of carbon (DIC, DOC, POC) and nutrients (DIN, DIP, DSi, DON, DOP, PN) were investigated bimonthly from August 1999 to August 2000 to study biogeochemical dynamics of carbon and nutrients in Tapong Bay, a small semi-enclosed and hypertrophic lagoon in southwestern Taiwan. The lagoon has only a tidal inlet for exchanging water between Tapong Bay and Taiwan Strait, which may result in low water exchange rates and various oxygen-deficient conditions in bottom water of the inner bay during warm seasons. The water exchange time of Tapong Bay ranges from 7 days (summer) to 13 days (winter) with a mean of 10 days. Nutrient dynamics were largely ascribed to allochthonous inputs, biological and exported removals in the lagoon. Diffusion fluxes from sediments to overlying water accounted for only about 7.6% of annual DIN inputs and 1.0% of annual DIP inputs. High primary productivity (89 mol C m⁻² year⁻¹) supported by abundant nutrients primarily drove the lagoon into a hypertrophic condition as particulate organic matter was derived mainly from biological production. Excess of DIP appeared to occur throughout the study period in the lagoon. Temperature, solar radiation and turbidity, rather than nutrients, perhaps controlled seasonal variations of primary productivity. The net ecosystem production (NEP) derived from daily changes of DOC and POC inventories was about 6.3 mmol C m⁻² day⁻¹ that was close to 6.7 mmol C m⁻² day⁻¹ simulated from the biogeochemical modeling. Therefore, the net ecosystem production (NEP) rate of organic carbon estimated from the biogeochemical model was reliable, and the NEP was temporally variable with an annual mean of 5.8 mol C m⁻² year⁻¹, implying that Tapong Bay was an autotrophic system. Although calcification proceeded pronouncedly in warm seasons, an invasion of CO₂ was significant in this system. In terms of nitrogen budget, the annual nitrogen fixation exceeded the annual denitrification with a magnitude of 1.30 mol N m⁻² year⁻¹, which may be supported by the abundance of nitrogen fixation microplanktons in the lagoon.