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61.
62.
铁道机车车辆电子产品的RAMS 总被引:6,自引:3,他引:3
根据IEC 62278-2002提出的铁道风险评估框架,阐述了铁道机车车辆电子产品的RAMS。对电子产品危害出现的频度进行了量化,对各种电子产品可能引发的危害严重等级进行了细化,并提出降低风险的3种设计对策。 相似文献
63.
In most developed countries motorized transportation is the dominant form of travel for long and short journeys. Transport-related
physical activity (TPA), however, is advocated as an appropriate transport mode for traveling short distances. The purpose
of this study is to explore the associations between private automobile availability, overall physical activity levels, and
TPA engagement in the adult population. A population-representative telephone survey assessed socio-demographics, private
automobile availability, overall physical activity levels, and travel to place of work/study and the convenience shop with
an adult sample (n = 2,000) residing in North Shore City, Auckland, New Zealand in April 2005. The majority of respondents reported unrestricted
(80%) or frequent (12%) private automobile availability. After controlling for covariates, binary logistic regression analyses
revealed those with no private automobile available were less likely to be classified as sufficiently active for health benefits
when compared to respondents with unrestricted private automobile availability. However, this finding was based on a small
minority (4%). Also, those reporting no private automobile availability were more likely to walk or cycle to place of employment
and the convenience shop when compared to those with unrestricted private automobile availability. Similar to other self-report
travel and physical activity survey tools, the questionnaire used potentially did not adequately capture TPA engagement. Future
TPA research needs to incorporate objective measures to address this issue.
相似文献
Hannah M. BadlandEmail: |
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李先强 《青岛远洋船员学院学报》2009,30(1)
海上专业学生的认识实习是改善航海类专业实践教学的重要手段,是理论教学成果转化为学生应用能力的重要途径.由于种种原因,学生海上认识实习问题一直未能得到很好的解决.通过分析国内外航海院校学生认识实习的基本情况,提出一条适合中国航海教育发展的认识实习之路非常必要. 相似文献
67.
基于动态贝叶斯网络的列控中心可靠性及可用性评估 总被引:1,自引:0,他引:1
为解决共因失效、动态失效及恢复机制等问题,本文基于动态贝叶斯网络对联锁车站和中继站列控中心可靠性及可用性进行评估.在分析列控中心系统结构的基础上构建系统动态故障树,并将动态故障树转化为动态贝叶斯网络,实现结构学习和参数学习.通过动态贝叶斯网络正向推理得到两种类型列控中心可靠度和可用度并进行比较分析.通过动态贝叶斯网络反向推理得到列控中心系统薄弱环节.研究系统敏感性因素并讨论恢复机制对系统可靠性及可用性的影响.结果表明:考虑共因失效的联锁车站和中继站列控中心的稳态可用度分别为0.999 960和0.999 977;电源及驱动采集单元为系统薄弱环节,需要重点关注.该方法能有效提高列控中心智能维修维护水平. 相似文献
68.
典型任务剖面内舰船机电单部件系统备件配置方法研究 总被引:3,自引:0,他引:3
根据舰船机电设备在典型任务剖面内的航渡、作战和撤离返航三个阶段不同故障特点,建立了任务周期内新的备件配置模型:航渡和撤离返航两个阶段利用以可用度为中心的Monte-Carlo仿真方法进行备件配置;作战阶段根据战损情况进行备件配置;系统总的备件配置数量等于三个阶段备件配置数量的和.计算实例表明,文中提出的备件配置方法能更准确地反映舰船系统备件的实际需求. 相似文献
69.
Estimates of emissions and energy consumption by vehicular fleet in India are not backed by reliable values of parameters, leading to large uncertainties. We report new methods, including primary surveys and secondary data sources, to estimate in-use fleet size, annual mileage (kilometers per year), and fuel efficiency of cars and motorised two-wheelers (MTW) for Delhi, and except fleet size and annual mileage of cars, for Visakhapatnam and Rajkot. We estimated that the official number of registered cars and MTW in Indian cities is more than two times the actual number of in-use vehicles. The private vehicular fleet in India is the youngest, its fuel efficiency one of the highest, and annual kilometers travelled is the lowest, compared to many high-income countries, such as the USA and those in European Union. Along with high renewal rate of fleet, the data suggest that it is possible for India to have one of the most fuel-efficient vehicle fleets in the world in the future, if fuel-efficiency standards and fiscal policies to contain growing dieselization are implemented in the country at the earliest. 相似文献
70.
LNG海上贸易作为世界天然气贸易的一种重要方式,得到了快速的发展。分析了世界LNG海运市场运量和运力的情况,并对未来市场的发展进行了展望。 相似文献