共查询到20条相似文献,搜索用时 93 毫秒
1.
2.
空气动力学特性直接影响车辆的稳定性、驾驶特性、安全性、操纵性及油耗。本文利用Fluent建立1:1的FSAE赛车模型,选择合适的数学模型进行三维流场的数值模拟。针对结构缺陷进行优化,增加了前后扰流板,扰流板使车辆阻力和升力都减小的同时,对汽车产生额外的地面附着力,它能抵消一部分气动升力,控制汽车上浮,使汽车能紧贴着道路行驶。仿真结果显示优化后的赛车压力分布更均匀、速度流线满足下压力要求、结构更加合理。 相似文献
3.
4.
5.
文章基于力学原理,对沥青混合料永久变形的各种试验方法的优缺点进行了比较,得出三轴重复荷载蠕变试验是评估沥青混合料永久变形的首选方案,其不仅能模拟道路的实际受力状态,而且能准确的进行车辙的计算和预估,值得推广应用。 相似文献
6.
文章研究了重型商用车辆分别采用推荐道路阻力与实测道路阻力对在底盘测功机上进行整车油耗试验的结果差异。结果表明,采用推荐道路阻力不能真实反应出车辆的油耗水平;底盘测功机的阻力设定直接影响车辆的油耗结果,阻力设定值越大,油耗越大,反之越小。 相似文献
7.
公路纵面视距行车安全性分析 总被引:1,自引:0,他引:1
驾驶员应有足够的视距来判断运行车辆前方环境发生的变化,如交通状况、道路线形组合形式及沿线景观设计等,以便采取相应措施确保汽车安全行驶。文章从道路纵面竖曲线设计原理出发,讨论了汽车安全行驶的条件,推导出停车视距与竖曲线设计长度、变坡角的关系,同时结合某高速公路安全性评价,对事故多发路段提出了合理化建议。 相似文献
8.
通过对道路营运里程编绘的研究,制定出规范性、权威性、实用性较强的道路营运里程地方标准,以适应全省经济发展和社会各界对道路运输的需要,促进全省经济和道路运输市场快速、健康、有序发展,为有关部门和广大道路运输从业人员提供车辆行驶和运费结算的依据,更好的为全省经济建设和道路运输事业服务. 相似文献
9.
10.
11.
In present study, a total of 3 types of light-duty vehicles were tested for 7 types of driving modes by using a vehicle dynamics-based simulation method. Deviations between the target and actual test vehicle speed and inaccurate chassis dynamometer road load settings are selected as the two main factors affecting the CO2 emission measurement test. 126 cases of simulations were conducted to analyze the effects of the deviation between the target and actual test vehicle speed on CO2 emissions and 63 cases of simulation were conducted to analyze the effectiveness of inaccurate road load test conditions on CO2 emissions. Then, the CO2 correlation method proposed by World Forum for Harmonization of Vehicle Regulations (WP.29, UN) was applied for simulated results in original simulation cases, and a correction to performance was validated by comparative analysis. From the simulation results, it is revealed that velocity and road load deviation are related to distinct changes in fuel efficiency and CO2 emission rates of test vehicles. Also, it is revealed that CO2 correction method show good performance to reduce the relative error lower than 2% in all test cases. 相似文献
12.
道路交通是造成气候变化的主要碳排放来源之一。目前针对道路交通碳排放量测量和减排效果的定量评估方面仍然存在较大挑战。综述了道路交通碳排放测量方法,将道路交通碳减排措施分为经济、技术和行政三类,根据角色定位总结了影响交通碳排放的需求、供应和环境三方面的主要因素。发现不同测量方法得出的碳排放量差异较大,且各种方法的准确性和适用范围也存在较大差异。目前的碳减排措施目标针对性不够强,且缺乏对政策效果的定量研究。亟需在未来研究中规范道路交通碳排放量的统计口径和误差标准,明确各交通主体的减排责任,将更多研究工作集中在减排措施效果的量化上。 相似文献
13.
14.
文章以广西柳南高速公路和桂柳高速公路的典型路面结构为研究对象,建立三维有限元模型,进行水泥混凝土路面结构模拟计算,分析水泥混凝土路面板与基层的层间接触状态对路面结构的挠度及荷载应力的影响。 相似文献
15.
半刚性基层裂缝的产生和发展很大原因是受到荷载作用,由交通荷载重复作用而造成的疲劳裂缝属于荷载型裂缝。文章结合广西路网工程建设实际状况,利用有限元计算模型分析半刚性基层受荷载作用开裂的情况,揭示基层荷载型裂缝对路面结构的影响。 相似文献
16.
《Transportation Research Part D: Transport and Environment》1999,4(2):109-125
Car exhaust emissions cause serious air pollution problems in many regions and, at a global level, contribute to climate change. Car use is also an important factor in other problems including traffic congestion, road accidents, noise pollution, community severance, and loss of countryside from road building. Forecasts of further increases in car ownership and use have prompted calls for policy-makers to encourage car users to switch to other forms of transport, particularly the bus. The effects of substituting bus for car travel in urban areas are simulated by specifying a spreadsheet model incorporating two types of car (petrol and diesel engine) and three types of bus (mini-, midi- and large bus). Six types of exhaust emission are considered for each vehicle type for the years 1992, 1995 and 1999: carbon monoxide, volatile organic compounds, nitrogen oxides, sulphur dioxide, (small) particulate matter and carbon dioxide. The paper provides a synthesis of monetary estimates of these exhaust emission and other costs. The other costs considered are traffic congestion, fuel consumption, noise pollution, road accidents and road damage. The exhaust emission monetary cost estimates, mainly from the United States and the United Kingdom, are discussed within the context of a sensitivity analysis which allows for changes in parameters such as load factors, emission factors and the individual exhaust emission cost estimates. The simulation results show that substitution of bus for car travel generally decreases the overall costs, particularly the costs of congestion, but increases exhaust emission costs if bus load factors are insufficiently high. In order to reduce exhaust emission costs from car to bus transfer at given load factors, the most effective policy option is to encourage the reduction of particulate emissions from bus engines. In terms of the overall costs, increasing bus load factors by relatively modest amounts can lead to substantial reductions in these overall costs. These results should be regarded as illustrative rather than definitive, given the uncertainties in a number of parameter estimates and the need for further research in areas not covered by the paper. 相似文献
17.
In this paper we study the problem of locating a new station on an existing rail corridor and a new junction on an existing road network, and connecting them with a new road segment under a budget constraint. We consider three objective functions and the corresponding optimization problems, which are modeled by means of mixed integer non-linear programs. For small instances, the models can be solved directly by a standard solver. For large instances, an enumerative algorithm based on a discretization of the problem is proposed. Computational experiments show that the latter approach yields high quality solutions within short computing times. 相似文献
18.
文章介绍了广西道路客运发展现状,分析了铁路发展对道路客运的影响,探讨了广西道路客运的优劣势和作用定位,并在此基础上提出了发展道路客运的原则、策略与措施。 相似文献
19.