Model-based control system design in a urea-SCR aftertreatment system based on NH3 sensor feedback

This paper presents preliminary control system simulation results in a urea-selective catalytic reduction (SCR) aftertreatment system based on NH₃ sensor feedback. A four-state control-oriented lumped parameter model is used to analyze the controllability and observability properties of the urea-SCR plant. A model-based estimator is designed via simulation and a control system is developed with design based on a sliding mode control framework. The control system based on NH₃ sensor feedback is analyzed via simulation by comparing it to a control system developed based on NO_x sensor feedback. Simulation results show that the NH₃ sensor-based strategy performs very similarly in comparison to a NO_x sensor-based strategy. The control system performance metrics for NO_x index, urea index, urea usage, and NH₃ slip suggest that the NO_x sensor can be a potential alternative to a NO_x sensor for urea-SCR control applications.     

Performance of air conditioners with a gas-liquid separation condenser and one-tank laminated evaporator

In this study, a parallel flow condenser and laminated evaporator for an automotive air-conditioning system were modified to improve performance. Gas-liquid separation type condensers, in which the condenser and receiver drier are integrated, and one-tank laminated type evaporators were developed, and their performances were investigated experimentally using HFC-134a. Heat transfer characteristics in the condenser are examined by means of air temperature, air velocity entering the condenser and inlet pressure of the refrigerant; heat transfer characteristics in the evaporator are examined by means of air temperature, relative humidity, flow rate of air, outlet pressure of refrigerant and superheat. Pressure drops for both evaporator and condenser are also measured, and correlations for pressure drop are derived for the condenser and evaporator, respectively. Air velocity and mass flow rate of the refrigerant have a significant effect on the overall heat transfer coefficient, and flow pass is not significantly influenced by the cooling capacity of the condenser. The overall heat transfer coefficient of the evaporator increases as air flow rate, air temperature and relative humidity increases.     

Flutter and Divergence Instabilities in Systems of Railway Wheelsets with Semi-rigid Articulation

For railway vehicles having coned wheels mounted on solid axles there is, in general, a conflict between stability of lateral deviations from the motion along the track and ability to steer round curves. However, certain configurations of three-axle vehicle can satisfy the requirement of perfect curving and for certain values of the system parameters are dynamically stable. In the case where three wheelsets have semi-rigid articulation and either the distribution of conicity amongst the wheelsets or the position of the articulation joint are varied, it is shown that both flutter and divergence instabilities can occur at low speeds, in contrast to the more common dynamic instabilities of other forms of railway vehicle which are driven by the inertia forces.     

一种最佳的汽车混合动力总成

介绍了对混合动力总成进行优化的建模及仿真工具《汽车快速性能优化及报告工具包—汽车系统模块(RAPTOR^TM—VSM)软件包》，指出了优化混合动力总成需在混合动力发动机、电动机、电池、超级电容器、动力总成配置和自动／手动变速器(AMT)控制器等方面做的工作。     

工厂火灾,爆炸场所危险度综合评价法

为减少火灾事故，介绍了“工厂火灾、爆炸场所危险度综合评价法”，“道氏法”是该法的基础。分析了“道氏法”的不足，而提出了固定危险和现实补偿的综合性计算方法。还通过实例记述了新方法的优点、基本原理和应用方法。该法能用于评价工厂企业危险设备、装置与场所的火灾、爆炸危险程度。     

不同外加剂对OGFC混合料路用性能的影响

OGFC为开级配沥青混合料,主要由粗集料嵌挤组成,在世界各地越来越广泛地用于铺筑路面.OGFC混合料可以增大路表面渗透性,减少噪音,增强表面摩擦力,尤其是在潮湿条件下.该文主要研究不同外加剂对OGFC路用性能的影响,其混合料分别由再生聚乙烯改性沥青(RPEB)、橡胶粉改性沥青(CRMB)和70#基质沥青+纤维与矿料拌和而成.并分别采用析漏试验、肯塔堡飞散试验、渗水试验、劈裂试验、静态模量试验,车辙试验和抗滑试验评估OGFC混合料的路用性能.结果表明:纤维和聚合物可以有效地减小OGFC离析的可能性,混合料每面击实50次能相应地提高磨耗性和其他相关的性能.改性沥青混合料的抗拉强度比(TSR)低于纤维+基质沥青混合料的抗拉强度比.     

Crash protection of Hybrid Electrical Vehicles for amending the KMVSS No. 91

This paper explores issues related to the electrical safety of Hybrid Electrical Vehicles (HEVs) during and after various crash events. Japanese and American federal regulations regarding occupant protection against high voltages in Electric Vehicles (EVs) and HEVs were surveyed and analyzed in this study. Front, side and rear impact tests for two types of HEVs were conducted to investigate electrolyte spillage, the retention of the propulsion battery system and the electrical isolation of the occupant. The test results met the related criteria. The test procedures and the criteria for occupant protection established through this study were amended to Korean Motor Vehicle Safety Standard (KMVSS) No. 91 to add the crash protection of the EVs and the HEVs.