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91.
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介绍了第三轨受流器的结构原理。分析比较了弹簧式和气压式受流器与第三轨接触压力调节方式的特点。基于电接触基本理论详细的阐述了受流滑板与第三轨接触区的导电机理。接触区域的导电电路由无数微小的电阻及电容并联而成,接触压力通过影响微小电阻、电容的数量比例,进而影响接触面上的导电能力和磨损性能。标称静态接触压力的设计值接近或等于"法向压应力临界值"时,导电能力和磨损特性取得均衡。 相似文献
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The rapid growth in air traffic has resulted in increased emission and noise levels in terminal areas, which brings negative environmental impact to surrounding areas. This study aims to optimize terminal area operations by taking into account environmental constraints pertaining to emission and noise. A multi-objective terminal area resource allocation problem is formulated by employing the arrival fix allocation (AFA) problem, while minimizing aircraft holding time, emission, and noise. The NSGA-II algorithm is employed to find the optimal assignment of terminal fixes with given demand input and environmental considerations, by incorporating the continuous descent approach (CDA). A case study of the Shanghai terminal area yields the following results: (1) Compared with existing arrival fix locations and the first-come-first-serve (FCFS) strategy, the AFA reduces emissions by 19.6%, and the areas impacted by noise by 16.4%. AFA and CDA combined reduce the emissions by 28% and noise by 38.1%; (2) Flight delays caused by the imbalance of demand and supply can be reduced by 72% (AFA) and 81% (AFA and CDA) respectively, compared with the FCFS strategy. The study demonstrates the feasibility of the proposed optimization framework to reduce the environmental impact in terminal areas while improving the operational efficiency, as well as its potential to underpin sustainable air traffic management. 相似文献
95.
Noise pollution in urban areas has many harmful effects on the citizens. There are varieties of noise generation sources of which the traffic noise could be a major source. The point which is perhaps less noticed is that sound level is not the only parameter to indicate the extent and intensity of noise pollution. Situation of urban land uses, distribution of population centers and types of passages can deeply affect the concern on this environmental issue but not with a similar ratio. This article presents an overlaying technique to define noise prone areas using all different factors involved. A case study was carried out in the District 14 of Tehran Metropolitan City where there are busy streets and highways. For this purpose, the share of each criterion in noise pollution intensity was determined using Analytical Hierarchy Process (AHP). Afterwards, the map layers were overlaid based upon the relative importance of the criteria to get the final map on which the noise prone areas are specified. The developed method could be used as a tool for indirect estimation of noise pollution by which instead of direct measurement of the equivalent sound level, it would be possible to predict noise susceptible areas considering the most important influential factors. 相似文献
96.
为了对比研究A类防撞等级中F型混凝土护栏和直壁型混凝土护栏的防护性能,建立两种护栏与客车的有限元模型,运用ANSYS Workbench软件中显式动力学模块,控制仿真碰撞的试验参数,将大客车模型以规定的初速度和碰撞角度进行计算机仿真碰撞试验,从车辆的加速度、车辆运行轨迹、护栏的最大动态变形量等方面综合对比两种护栏的防护性能。结果表明:相比直壁式护栏,F型混凝土护栏防撞性能、安全性能、导向性能较好。 相似文献
97.
对轨道交通车辆多层复合结构的隔热壁进行隔热性能理论计算与仿真计算的对比,对隔热壁内部空气层的隔热性能进行分析。结论为:在车辆多层复合结构的隔热壁K值计算中,当空气层厚度大于一定厚度时,流体自然对流对隔热壁的隔热性能影响较大。利用多项式密度(Polynomial Denisity)和Boussinesq模型两种算法,对所得结论进行了验证。 相似文献
98.
朱伟鹏 《现代城市轨道交通》2021,(4):38-41
牵引传动系统是轨道交通车辆装备实现机电能量转换的“心脏”单元,其性能在某种程度上决定轨道交通车辆的动力品质、能耗和控制特性,是轨道交通车辆节能升级的关键系统。而永磁同步牵引系统以其高效率、高可靠性和低能耗的优势特点,受到轨道交通行业的密切关注。文章阐述深圳地铁10号线永磁同步牵引系统批量装车概况,重点分析永磁同步牵引系统组成及优势,指出推广应用永磁同步牵引系统的经济和社会效益显著。 相似文献
99.
Transportation is a major cause for environmental degradation via exhaust emissions. For many transit-oriented metropolitan areas, bus trips often constitute a sizeable mode share. Managing the bus fleet, in particular updating buses to comply with the newer emissions standards, therefore, can have a substantial impact on transportation-induced air quality. This paper presents the approach of remaining life additional benefit–cost (RLABC) analysis for maximising the total net benefit by either early-retiring or retrofitting the current bus fleet within their lifespans. By referring to the net benefits for different bus types estimated by RLABC analysis, the most beneficial management scheme for the current bus fleet can be identified. Optimal bus fleet management (BFM) models based on the RLABC analysis for the operator and the government are developed. Then a government subsidy plan is produced to achieve win–win solutions, which will offer efficient and flexible management schemes. To illustrate the approach, the largest bus company in Hong Kong, which carries more than 23% of the total trips in Hong Kong, is taken as a case study example. Instead of adopting a fixed retirement plan, such as replacing buses at the age of 17 as is currently practised, the proposed method develops an optimal BFM scheme that progressively phases out buses or retrofits them. This study produces promising results to demonstrate the large benefit of this approach for optimal bus fleet management. 相似文献
100.