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221.
从机车在"0位"时柴油机晃动现象入手,对"柴油机振动烈度评定方法"进行了分析探讨。重点对测量点、测量参数计算、评定准则进行了阐述,重新提出了"柴油机振动烈度评定方法",同时给出了振动位移的控制值。 相似文献
222.
面向高速铁路的CTCS+ATO列控系统研究 总被引:3,自引:3,他引:0
《铁道标准设计通讯》2017,(4):153-158
为提高高速铁路运输效率和自动化程度,根据珠三角城际铁路CTCS2+ATO列控系统的运用经验,提出高速铁路引入自动驾驶(ATO)的方案。方案采用CTCS+ATO系统结构,根据系统配置分为CTCS+ATO-PFC(Partial Function Configuration)和CTCS+ATO-FFC(Full Function Configuration)两个等级。分别对每个等级的系统功能、地面和车载设备配置进行定义,并提出系统分级实施方案。CTCS+ATO列控系统方案综合考虑我国列控系统的现状和发展方向,为我国高速铁路引入自动驾驶提供参考依据。 相似文献
223.
为弥补中国现行桥梁规范中计算动力冲击系数时考虑因素单一的不足,对冲击系数的影响因素进行研究,并提出更合理的冲击系数建议值。首先,根据中国桥梁通用图集建立13座不同截面形式和不同跨径的常见中小跨径公路混凝土简支梁桥的有限元模型,结合能表征中国设计车辆荷载动力特性的三维车辆数值模型,建立车桥耦合振动分析系统。然后,基于车桥耦合振动分析系统,研究桥梁基频、桥面不平整度、车速和车质量等因素对动力冲击系数的影响,并与中国现行桥梁设计规范中的动力冲击系数取值进行对比分析。最后,提出冲击系数的建议值,并与世界各国桥梁规范中的冲击系数取值进行对比,讨论建议值的合理性。结果表明:桥面不平整度是影响冲击系数的重要因素,在桥面好的情况下,冲击系数均在0.1以下,低于规范中规定的冲击系数,而桥面很差时,冲击系数可达0.5,远大于中国现行规范中的冲击系数设计值,因此,定期对桥面进行维护能有效减小车辆对桥梁的冲击效应;质量轻的车辆引起更大的冲击系数,但由于车辆总质量轻,其导致的总荷载效应仍然较小,而重车虽然引起的冲击系数较小,但由于其导致的总荷载效应较大,更易对桥面造成损伤,因此,限制超载尤为重要。 相似文献
224.
225.
杨忠 《南通航运职业技术学院学报》2008,7(2):65-69
随着船舶维修制度的变革,油液监控技术逐渐应用于船舶领域,成为机械状态监控应用研究领域比较活跃的一个分支,文章主要阐述油液监控技术在船舶中的应用。 相似文献
226.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(3):421-442
This paper presents the influence of dynamic and geometrical soil parameters on the propagation of ground vibrations induced by external loads. The proposed approach is based on a three-dimensional model, focusing on realistic excitation sources like impulse loads and moving railway vehicles. For the latter, a complete vehicle/track model is developed. The simulation is performed in time domain, offering an interesting approach, compared with classic cyclic analyses. The ground is modelled initially as an elastic homogeneous half-space and additionally as a layered half-space. First, the effect of homogeneous soil properties on ground vibration is analysed. Soil stratification is then taken into account, using various configurations. Analysis reveals that as receiver distance increases ground wave reflection in a layered ground plays an important role in the reduction of ground surface motion. This effect is magnified when the phase velocity wavelength becomes large compared with the depth of the surface layer. 相似文献
227.
The need for a Global Ocean Observing System Global (GOOS) is now widely appreciated. Parts of GOOS are currently being implemented already. In this paper, written on the request of the joint Scientific and Technical Committee of GOOS, we present some of the scientific issues that need to be addressed for the further development of the Ocean and Marine Meteorology Service module of GOOS. This module is concerned with monitoring and prediction of sea level (both tsunamis and storm surges) and wind driven waves (wind–sea and swell), among other things. For each of these we discuss the current state-of-the-art, indicate what observations are needed and make suggestions for future modelling development. 相似文献
228.
229.
The North Bay of Biscay continental shelf is a major French demersal fishery, but little was known on the trophic food web of its benthic communities. In order to determine the benthic trophic web, the objectives of this study are to describe the macro- and megafaunal benthic community structure (species richness, abundance and biomass) and to establish the trophic pathways (food sources and trophic levels) by applying carbon and nitrogen stable isotopic analysis to the main benthic and demersal species (invertebrates and fish). Two distinct benthic communities have been identified: a muddy sand community within the central part of the bay, and an outer Bay of Biscay Ditrupa sand community of higher species richness, abundance and biomass than the muddy sand community. Deposit-feeders, suspension feeders and predators, distributed in three main trophic levels, dominate both communities. Large differences in stable carbon ratio values within the primary consumers provide evidence of two different food sources: i) a pelagic food source made up of recent sedimenting particulate organic matter on which zooplankton and suprabenthos feed and ii) a benthic detrital food source supplying deposit feeders and partly benthic suspension feeders. Differences in isotopic signatures were also observed within the upper trophic levels that allowed estimation of the contribution of each food source component to the diet of the upper consumers. Finally, the use of stable isotopic composition together with the species' feeding strategy allow identification of the main differences between the trophic functioning of the two benthic communities and highlight the importance of the role of detrital pathways in the carbon cycling within the continental shelf benthic trophic web. 相似文献
230.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(6):711-733
The traction control system (TCS) might prevent excessive skid of the driving wheels so as to enhance the driving performance and direction stability of the vehicle. But if driven on an uneven low-friction road, the vehicle body often vibrates severely due to the drastic fluctuations of driving wheels, and then the vehicle comfort might be reduced greatly. The vibrations could be hardly removed with traditional drive-slip control logic of the TCS. In this paper, a novel fuzzy logic controller has been brought forward, in which the vibration signals of the driving wheels are adopted as new controlled variables, and then the engine torque and the active brake pressure might be coordinately re-adjusted besides the basic logic of a traditional TCS. In the proposed controller, an adjustable engine torque and pressure compensation loop are adopted to constrain the drastic vehicle vibration. Thus, the wheel driving slips and the vibration degrees might be adjusted synchronously and effectively. The simulation results and the real vehicle tests validated that the proposed algorithm is effective and adaptable for a complicated uneven low-friction road. 相似文献