排序方式: 共有72条查询结果,搜索用时 31 毫秒
21.
重庆跨座式单轨系统限界检测设备的研究 总被引:3,自引:1,他引:2
徐银光 《铁道标准设计通讯》2005,(2):85-87
跨座式单轨系统限界有其特殊性 ,尺寸控制非常紧 ,内容多而复杂。因此 ,该系统土建工程施工完后必须对全线断面的建筑限界进行检测。要进行准确高效的检测 ,需研发移动式检测设备 (限界检测车 )。在对跨座式单轨车系统限界分析研究的基础上 ,提出限界检测车的总体技术构想。 相似文献
22.
J. Y. Kim D. H. Jung C. H. Jeong H. J. Choi 《International Journal of Automotive Technology》2014,15(6):961-966
The current test methods are insufficient to evaluate and ensure the safety and reliability of vehicle systems for all possible dynamic situations, including the worst case scenarios such as rollover, spin-out and so on. Although the known NHTSA Sine with Dwell steering maneuvers have been applied for the vehicle performance assessment, they are not enough to estimate other possible worst case scenarios. Therefore, it is crucial for us to verify the various worst case scenarios, including the existing severe steering maneuvers. This paper includes useful worst case scenarios based upon the existing worst case scenarios mentioned above and worst case evaluation for the vehicle dynamic controller in a simulation basis and UCC HILS. The only human steering angle was selected as a design parameter here and optimized to maximize the index function to be expressed in terms of both yaw rate and side slip angle. The obtained scenarios were enough to generate the worst case scenario to meet NHTSA worst case definition. It has been concluded that the new procedure in this paper is adequate to create other feasible worst case scenarios for a vehicle dynamic control system. 相似文献
23.
J. Y. Kim C. H. Jeong M. J. Jung J. H. Park D. H. Jung 《International Journal of Automotive Technology》2013,14(6):965-970
Traffic accidents are caused by various factors, which can be classified into human factors, vehicle factors and environmental factors. Recently, human factors have been drawing particular attention as efforts are being made to enhance the safety performance of vehicles and improve road conditions. Driving distraction caused by an increased driving workload is a representative human factor. Various studies in the past have attempted to quantify the driving workload by using EEG activities. However, they have failed to consider vibration properties generated from vehicle engines. A number of noise signals were included in brainwave signal processing, which resulted in a failure to obtain reliable outcomes. Thus, this study suggests driver EEG activities free of vehicle engine secondary vibration in order to develop a method that analyzes the driving workload with high statistical reliability. By using the analytical method developed in this study, standard values of driving workload for straight and left-turn driving that has statistical significance could be calculated. The analytical method for driving workload created by this study can be applied to HVI and road design. 相似文献
24.
25.
G. S. Jung Y. H. Sung B. C. Choi M. T. Lim 《International Journal of Automotive Technology》2009,10(1):1-7
Compression ignition of homogeneous charges in internal combustion (IC) engines is expected to offer high efficiency of DI
diesel engines without high levels of NOx and particulate emissions. This study is intended to find ways of extending the
rich limit of HCCI operation, one of the problems yet to be overcome. Exhaust emissions characteristics are also explored
through analyses of the combustion products. DME fuel, either mixed with air before induction or directly injected into the
combustion chamber of a rapid compression and expansion machine, is compressed to ignite under various conditions of compression
ratio, equivalence ratio, and injection timing. The characteristics of the resulting combustion and exhaust emissions are
discussed in terms of the rate of heat release computed from the measured pressure, and the concentrations of THC, CO, and
NOx are measured by FT-IR and CLD. The experimental data to date show that operation without knock is possible with mixtures
of higher equivalence ratio when DME is directly injected rather than when it is inducted in the form of a perfectly homogeneous
fuel-air mixture. Although fuel injected early in the compression stroke promotes homogeneity of the DME-air mixture in the
cylinder, it causes the mixture to ignite too early to secure good thermal efficiency and knock-free operation at high loads.
Low temperature reactions occur at about 660K regardless of the fueling methods, fuel injection timing and equivalence ratio.
The main components of hydrocarbon emissions turned out to be unburned fuel (DME), formaldehyde and methane. 相似文献
26.
佘健 《重庆交通大学学报(自然科学版)》1999,18(4)
采用近景摄影的方法, 以获取隧道开挖的实态轮廓线, 从而获得任意断面的超挖、欠挖数据. 另外, 通过前后两次的测摄可获取围岩的变形数据, 利用以上数据可对隧道围岩结构进行受力分析、计算, 也可确定最佳二次衬砌时间. 相似文献
27.
Safety mechanism is required for an automotive battery pack to prevent thermal failure which could lead to catastrophic events. Passively cooled battery packs can prevent thermal failure by conducting adaptive control of battery power without any external cooling device. The key to this power control is how to secure battery safety while minimizing energy loss. This paper proposes a novel, adaptive power control strategy for automotive passive-cooling battery packs. Four different cases with electrochemical battery model are simulated and compared to each other according to a city driving profile. Driving simulation result confirmed that the present power control algorithm is an effective solution for preventing thermal failure along with improving energy efficiency of automotive battery packs. 相似文献
28.
Kwang Hyo Jung Kyung Chun Kim Sang Youl Yoon Seong Hun Kwon Ho Hwan Chun Moon Chan Kim 《Journal of Marine Science and Technology》2006,11(4):270-278
Stereoscopic particle image velocimetry measurements were made in a wind tunnel using a prototype waterjet model. The main
wind tunnel provided the vehicle velocity and a secondary wind tunnel was set up as the waterjet propulsion model. Pressure
distributions along the ramp and lip sides inside the duct were measured for three jet velocity to vehicle velocity ratios.
Three-dimensional velocity fields were obtained at the intake entrance and the nozzle exit of the waterjet system. The flow
into the duct was faster in the lip region than on the ramp side. Because of the variation in intake geometry from a rectangular
to a circular section and because of the sudden curvature change on the lip side, a pair of counter-rotating vortices was
observed in the mean velocity field at the nozzle exit. In addition, the turbulent kinetic energy correlated with the vortex
pair was stronger on the lip side than in other areas. Dominant large-scale structures were extracted by using a snapshot
proper orthogonal decomposition analysis. It was found that most of the turbulent kinetic energy was attributed to at least
three vortices near the nozzle exit. This detailed three-dimensional velocity field will be useful for the verification of
CFD simulations applied to the waterjet system. 相似文献
29.
通过正交试验研究二灰碎石各种材料用量(二灰内比、碎石比例和级配、水泥掺量等)与二灰碎石基层强度的关系,旨在从力学角度得到抗裂性能较佳的半刚性材料.结果表明,水泥掺量是影响二灰碎石早期强度的主要因素,其次是二灰内比.另外,适当增加碎石比例和粗集料含量,可以提高强度和减少收缩裂缝. 相似文献
30.
Among dispatching control approaches, the holding option has attracted the most attention in bus control. However, holding a vehicle at a transfer station may exacerbate the delays because more passengers might accumulate at downstream stations and may also affect other connecting routes at other transfer stations. Our problem is to minimize the total costs of dispatching ready vehicles at each transfer station along coordinated routes in a multi‐hub transit network. The total costs include the waiting cost for on‐board passengers, the missed connection costs for late arrival passengers at the subject transfer station and possible transfer costs at downstream transfer stations. We develop a heuristic algorithm to optimize the holding times based on real time information about late vehicles. The results show that ready vehicles should be held longer when the arrival variances of late vehicles are small or when many late connecting passengers are expected. 相似文献