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61.
H. Christopher Frey Kangwook Kim 《Transportation Research Part D: Transport and Environment》2009,14(8):585-592
In-use micro-scale fuel use and emission rates were measured for eight cement mixer trucks using a portable emission measurement system. Each vehicle was tested on petroleum diesel and B20 biodiesel. Average fuel use and emission rates increase monotonically versus engine manifold absolute pressure. A typical duty cycle includes loading at a cement plant, transit while loaded from the cement plant to work site, creeping in a queue of vehicles at the worksite, unloading, and transit without load from the site to the plant. For B20 versus petroleum diesel, there is no significant change in the rate of fuel use, CO2 emissions, and NO emissions, and significant decreases in emissions for CO, hydrocarbons, and particulate matter. For loaded versus unloaded onroad travel, fuel use and CO2 emissions rates are approximately 60% higher and the rates for other pollutants are approximately 30–50% higher. A substantial portion of cycle emissions occurred at the work site. Inter-vehicle and intra-cycle variability are also quantified using the micro-scale methodology. 相似文献
62.
基于生命周期评价理论,对高速铁路生命周期二氧化碳排放计算的边界进行界定,将高速铁路的生命周期划分为基础设施建造、运营和回收3个阶段;根据对各阶段高速铁路二氧化碳排放清单的分析,分别给出各个阶段二氧化碳排放的计算式;通过算例分析了高速铁路在建造和运营阶段碳排放的特点.分析和数值计算结果表明,虽然在高速铁路基础设施建设过程中由于大量建设材料和高能耗施工机械的使用,使得高速铁路建造阶段的二氧化碳排放量相对较多;但是,由于高速铁路具有节约能源、节省土地和货运增量替代效应等特点,使得高速铁路进入运营阶段后二氧化碳的排放量大幅度减少,即从生命周期全过程来看,高速铁路具有较好的减排效果. 相似文献
63.
IntroductionA promising way to stimulate physical activity is to promote the choice for active modes of transport (walking and cycling). Over the past years, several interventions and policies have been implemented to stimulate this mode shift. However, information concerning the effectiveness of these interventions and policies is still limited. The aim of the present study was to systematically review the effectiveness of interventions designed to stimulate a shift from car use to cycling or walking and to obtain insight into the intervention tools that have been used to promote and/or implement these interventions.MethodsFive databases were searched and articles published in English, Dutch, German, Danish, Norwegian and Swedish were included. Only studies that focussed on a mode shift from car use towards active transport in a general adult population, which were published in peer reviewed journals and which investigated effectiveness were included. Intervention tools used were categorized by using the model of Hoogerwerf & Herweijer, as either legal, economic (subsidy, reward system, penalty), communicative (written materials, behavioural tools) and physical tools (providing bicycles, providing better bicycle facilities at work, adjustment of the environment).ResultsNineteen studies met our inclusion criteria. Studies included described work-place-based interventions, architectural and urbanistic adjustments, population-wide interventions, and bicycle-renting systems. Nearly all studies (except three) showed positive effects concerning a mode shift. Most of the included studies used more than one intervention tool and the tools used differed between types of interventions. However, information about the statistical significance of these results was often lacking and the study methodologies used were not of high quality.ConclusionNearly all studies showed results in a positive direction. However, the quality of the included studies was mostly low and intervention characteristics were poorly described. 相似文献
64.
BIM在铁路设计中的应用探讨 总被引:3,自引:3,他引:0
《铁道标准设计通讯》2016,(8):17-20
通过阐述建筑信息模型(BIM)概念,分析基于BIM技术的全生命周期理念的建筑优势,并介绍BIM技术在国内外建筑业及国内铁路行业的发展现状,提出铁路设计应用BIM的5个关键点:与GIS技术结合、综合管线碰撞检测、站场运营管理、协同设计与作业、项目各阶段的衔接,总结国内BIM发展存在的问题:行业标准缺失、三维协同设计理念缺乏、专业软件不足、市场认知与人才培养问题,并提出对应的推行BIM策略,最后提出BIM将引领铁路建设向信息化、智能化发展。 相似文献
65.
提出吸收式制冷复合循环新模式,讨论了复合循环的热力计算。单效/双效复合循环有高低压2个发生器,高压发生器由高温级热源驱动,低压发生器由来自高压发生器的冷剂蒸汽与低温级热源联合驱动,实现高低温级热源的能量梯级利用。作为实例,对由高低温两级增压空气中冷器驱动的单效/双效复合循环进行了热力计算,并与单效循环和双效循环进行了热力性能比较。结果表明,复合循环的热力系数和制冷量均比单效循环高出15%,复合循环的余热利用量和制冷量分别高出双效循环153%和110%。 相似文献
66.
基于灰色预测模型的某型导弹费用研究 总被引:3,自引:0,他引:3
随着导弹武器装备技术含量提高、组成变复杂,各种费用也随之增加,对其费用的分析具有涉及范围广、时间跨度大、变量多及数据离散等特点。分析此类系统的特点,利用灰色理论的对其费用进行研究,并从某型导弹有限的寿命周期费用数据出发,建立GM(1,1)模型进行预测,结果较好。 相似文献
67.
以成功应用于京沪线提速工程中的自动闭塞系统为例,介绍了ZPW-2000A的试验流程和模拟试验方法,并针对ZPW-2000A特有的小轨道探讨了模拟方案. 相似文献
68.
宋谦 《武汉船舶职业技术学院学报》2005,4(5):17-20
阐述了多点巡回检测控制系统的构成方法,对具体电路进行了分析,用计算机软件发射编码信号及控制命令,对报警探头状态进行了判别. 相似文献
69.
70.
The Arabian Sea exhibits a complex pattern of biogeochemical and ecological dynamics, which vary both seasonally and spatially. These dynamics have been studied using a one-dimensional vertical hydrodynamic model coupled to a complex ecosystem model, simulating the annual cycle at three contrasting stations. These stations are characterised by seasonally upwelling, mixed-layer-deepening and a-seasonal oligotrophic conditions, respectively, and coincide with extensively measured stations on the two JGOFS ARABESQUE cruises in 1994. The model reproduces many spatial and temporal trends in production, biomass, physical and chemical properties, both qualitatively and quantitatively and so gives insight into the main mechanisms responsible for the biogeochemical and ecological complexity. Monsoonal systems are typified by classical food web dynamics, whilst intermonsoonal and oligotrophic systems are dominated by the microbial loop. The ecosystem model (ERSEM), developed for temperate regions, is found to be applicable to the Arabian Sea system with little reparameterisation. Differences in in-situ physical forcing are sufficient to recreate contrasting eutrophic and oligotrophic systems, although the lack of lateral terms are probably the greatest source of error in the model. Physics, nutrients, light and grazing are all shown to play a role in controlling production and community structure. Small-celled phytoplanktons are predicted to be dominant and sub-surface chlorophyll maxima are robust centers of production during intermonsoon periods. Analysis of carbon fluxes indicate that physically driven outgassing of CO2 predominates in monsoonal upwelling systems but ecological activity may significantly moderate CO2 outgassing in the Arabian Sea interior. 相似文献