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61.
Objectives: Public transport vehicles (PTVs) play a decisive role in development of the urban economy. However, the safety of PTVs is threatened by the man-released chemical or arson attack. It was found that indoor air safety can be greatly improved by employing air-rain ventilation instead of the common ventilation in a PTV.Methods: Numerical simulations and experiments have been done to prove the effectiveness of the air-rain flow against chemical attack or arson in PTVs.Results: The research shows that, during a chemical attack, an air-rain flow of 0.1 m/s can constrain the spread of a chemical agent in a very limited zone near its source, which is far away from the passengers’ breathing area in the PTV. During an arson attack, at an air-rain flow of 0.3 m/s, most of the area in the PTV maintains a low temperature for at least 60?s during a fire, which is long enough for passenger evacuation.Conclusion: Compared to common ventilation, the key characteristic of air-rain ventilation is its resistance to the blending effect of the air. Because of this, the spread of chemical agents, hot gas/combustion products during a fire, and fuel aerosol is constrained to a limited area in a PTV. Passengers are then protected from chemical attack, explosion of fuel aerosols, and high temperatures and smoke. Thus, we can say that this new ventilation mode increases passenger safety in buses. 相似文献
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《Journal of Manufacturing Processes》2014,16(2):276-283
The automotive industry is developing designs and manufacturing processes for new generations of electric motors intended for use in hybrid and electric vehicles. There is interest in replacing the aluminum traditionally used in induction motor rotors with copper to improve motor capability. This paper focuses on solid-state welding to join copper end rings to copper spokes in the fabrication of copper rotors. Inertia friction welding was explored to examine weldability of these copper components. A better understanding of inertia welding characteristics will help the advancements in its application for induction rotors. The limitations of this application are discussed. 相似文献
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Dale E. Heydlauff 《Environmental management》1996,20(6):963-966
The quality and sustainability of the natural environment is a matter of inestimable value and is critical to public health and welfare. All species have a purpose, and they exist for the betterment of other species. It is, therefore, incumbent on all humans to do their part in the preservation of this vast, diverse ecosystem called Earth. All humans are the beneficiaries, the ultimate customers, of a sound environment—water that is safe to drink, air that can be breathed, and soil that will sustain crops. There must be a commitment to leaving a clean and healthy planet for generations to follow, an earth which is enhanced, not diminished, by humans' presence. 相似文献
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近年来,电动汽车因其在行驶过程中无任何尾气排放,被各国政府视为推动交通部门清洁、低碳发展的重要途径,主要发达国家纷纷推出了各自的电动汽车发展战略。但是,由于电力属于二次能源,其上游电力生产阶段的能源消费是否清洁将对电动汽车的减排效果产生重要影响。考虑到目前中国绝大部分电力源于煤炭,电动汽车是否真正有益于减排还有待进一步验证。目前一些专家和学者基于传统的过程生命周期评价方法对电动汽车的能源消费、温室气体排放做了一些研究,但研究结果差异较大。为了对电动汽车的减排效果进行更精确的研究,本文采用混合生命周期方法对电动汽车的能源消费、温室气体排放进行了计算。同时,在考虑电动汽车的燃料生命周期、车辆制造生命周期的基础上,将相关配套充电设施建设生命周期纳入到电动汽车的全生命周期系统边界内,以使对电动汽车全生命周期的研究结果更加完整、精确。研究结果显示,纯电动汽车并非是"零排放"的,在燃料周期,虽然纯电动汽车的单位里程能源消费强度较小,约为传统汽油车的94.6%,但以煤为主的高碳电力结构导致目前纯电动汽车燃料周期的单位里程温室气体排放强度约为传统汽油车的1.12倍;车辆周期内,纯电动汽车的能源消费和温室气体排放量也略高于传统汽油车;此外,配套充电设施的建设也将增加纯电动汽车全生命周期的能源消费和温室气体排放量。综合燃料、车辆及充电设备的全生命周期,在当前的电源结构及技术条件下,电动汽车虽然具有较高的能源效率和较好的石油替代效果,但其全生命周期内的煤炭消费较高,导致其温室气体排放量高于传统汽油车,在当前的情况下大规模发展电动汽车并不利于温室气体减排。 相似文献
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Assessment of New Vehicles Emissions Certification Standards in the Metropolitan Area of Mexico City 总被引:1,自引:0,他引:1
Light duty gasoline vehicles account for most of CO hydrocarbons and NOx emissions
at the Metropolitan Area of Mexico City (MAMC). In order to ameliorate air pollution from the beginning of 2001, Tier 1 emission standards became mandatory for all new model year sold in the country. Car manufacturers in Mexico do not guarantee the performance of their exhaust emissions systems for a given mileage. The purpose of this study was to assess whether the Tier 1 vehicles will stand the certification values for at least 162000 km with the regular fuel available at the MAMC. Mileage accumulation and deterioration show that certified carbon monoxide emissions will stand for the useful life of the vehicles but in the case of non-methane hydrocarbons will be shorter by 40%, and nitrogen oxides emissions above the standard will be reached at one third of the accumulated kilometers. The effect of gasoline sulfur content, on the current in use Tier 1 vehicles of the MAMC and the impact on the emissions inventory in year 2010 showed that 31000 extra tons of NOx could be added to the inventory caused by the failure of the vehicles to control this pollutant at the useful life of vehicles. 相似文献
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