Stability measurement of high-speed vehicles

Vehicle rollover represents a significant percentage of single-vehicle accidents and accounts for over 9000 fatalities and over 200,000 non-fatal injuries each year. Previous research has yielded rollover stability control systems that are effective in on-road conditions. Accident statistics show, however, that over 90% of rollovers involve road departure, during which a vehicle may encounter sloped and rough terrain while travelling at high speed. A critical element of most rollover stability control systems is a metric that monitors a vehicle's nearness to rollover. Most metrics, however, are designed for use on flat, level surfaces characteristic of on-road terrain. In this paper, a new stability metric, termed the stability moment, is proposed that is accurate on terrain surfaces with arbitrary geometry, which allows it to be used in road departure scenarios. The metric is based on an estimate of the distribution of wheel–terrain contact forces. The metric can be calculated on line in real time, using only practical, low-cost sensors. The metric is compared in simulations and experimental studies to existing stability metrics and is shown to exhibit superior performance, particularly in off-road conditions.     

Communicating something confidential while travelling by train: the use of a telephone conversation versus silent modes

Wireless ICTs are often used in public transport. Using survey data collected amongst 98 train travellers this article aims to gain insight into important factors that affect train travellers’ intentions to communicate with distant others while travelling. More specifically, the focus is on the decision-making process that leads to the intention to choose for a confidential conversation either via ‘audible’ mobile phone or via ‘silent’ SMS/e-mail. An approach that is related to the Extended Model of Goal-directed Behaviour (EMGB) is applied. Structural equation modelling results indicate that in particular past SMS behaviour, the desire to communicate (goal desire), the perceived efficacy and controllability influence the intention to conduct a confidential phone conversation in the train. The influence of the social environment (e.g. eavesdropping) seems to be less important. Several EMGB constructs are strongly influenced by age. It seems that older respondents have more negative attitudes towards telephoning while travelling by train, and find it more difficult to call other people in such a situation. Finally, they have a lower intention than younger respondents to conduct a confidential conversation over the phone while travelling.

Improvement in the estimation and back-extrapolation of CO2 emissions from the Irish road transport sector using a bottom-up data modelling approach

Road transport is a major source of CO₂ emissions in Ireland and accounts for almost 96% of the total CO₂ emissions from the transport sector. Following the recent adopted UNFCCC reporting guidelines on annual inventories [24/CP.19], this study applied the 2006 IPCC Guidelines for National Greenhouse Gas Inventories (2006 IPCC GLs) tier 3 approach to estimate CO₂ emissions from road transport at the vehicle category level, for the first time in Ireland. For this, disaggregated datasets were prepared based on year of vehicle registration and mileage since registration of the vehicle. Such an approach provided a more realistic national scenario in comparison to the use of average mileage degradation in emission calculations. This investigation comprised a recalculation of previous emissions estimates (1990–2012) and an estimation of CO₂ emissions in 2013 using a previously unavailable level of data disaggregation for vehicle mileage as well as using vehicle class specific data and an improved bottom-up estimation methodology in COPERT. Historic vehicle fleet data were restructured, annual mileage data were estimated in relation to the fleet data and back extrapolated using a regression approach.The results showed that the mileage degradation was not only subject to fuel technology, engine size, and age but also the emissions class and vehicle category. It was also observed that the disaggregated level of data provided a different CO₂ emissions split among the vehicle categories than that of previous estimations which were based on an aggregated level of data. Previous emissions inventories (1990–2012) were shown to have underestimated the share from diesel fuelled passenger cars by more than 56% in 2012. Diesel fuelled passenger cars were also found to account for the majority of CO₂ emissions from road transport activities in Ireland in 2013. The level and trend assessment showed that emissions from Euro-II and Euro-III classed vehicles especially for passenger cars, which have a significant contribution to the total emission in 2013 have caused an increase in fleet level emissions in Ireland. In addition, the results also showed that the emissions share from Light Duty Vehicles and Heavy Duty Vehicles were overestimated by previous investigations. This paper highlights the importance of the resolution of data used in emissions inventory preparation which may impact upon future projections and policy formulation. The findings of this investigation are also discussed in relation their implications for road transport policy, including carbon taxation and future policy options aimed at achieving EU emissions target in 2020.     

Demand and welfare effects in recreational travel models: Accounting for substitution between number of trips and days to stay

In this paper we present a non-linear demand system for households’ joint choice of number of trips and days to spend at a destination. The approach, which facilitates welfare analysis of exogenous policy and price changes, is used empirically to study the effects of an increased CO₂ tax. In particular, we focus on the effect of including substitution between households choice of the number of trips and days to spend at a destination in the welfare analysis. The analysis reveals that the equivalent variation (EV) measure, for the count data demand system, can be seen as an upper bound for the households welfare loss. Approximating the welfare loss by the change in consumer surplus, accounting for the positive effect from longer stays, imposes a lower bound on the households welfare loss. The difference in the estimated loss measures, from the considered CO₂ tax reform, is about 20%. This emphasizes the importance of accounting for substitutions toward longer stays in travel demand policy evaluations.     

基于特征线的客车造型设计方法研究

以造型法则为基础,探讨一种以特征线为依托的设计方式,力求使客车的设计过程变得简单明了,使设计师的思路更加清晰。     

客车有限元建模方法概述

针对国内客车行业要求,在现有客车有限元建模技术的基础上,研究新的更切合客车产品特点的有限元建模方法,通过实际应用表明,这种方法是实用有效的。     

旅游城市的公共自行车网络规划方法研究

为了对景区公共自行车站点进行合理布设,研究通过对相关文献的综合归纳,以及对国内自行车交通发展现状的分析,提出了以二次指数平滑法进行需求量预测、p-中位模型进行站址规划、模糊综合评判法进行站址评价的旅游城市景区公共自行车网络规划设计方法,并以大唐芙蓉园景区为例,进行了实例分析。结果表明所提出的方法能为旅游景区的公共自行车站点分布进行合理的规划。     

柔性神经网络及其在开关磁阻电机建模与仿真中的应用

作为一种新型的神经网络,创建了具有高度柔性特性的网络结构,给出了柔性神经网络(FNN)的基本原理,并将其应用于开关磁阻电机(SRM）的建模与仿真,展示了SRM新型建模方法的主要优点。FNN在实现系统功能的同时,需要较少的神经元和迭代循环,大大降低了网络的复杂性,加速了网络的学习与实时计算速度。     

Putting our money to good use: Can we attract more passengers without increasing subsidies?

This paper evaluates the policy of Swedish public transport authorities, determining whether the number of trips on local public transport could have been increased without increasing subsidies. Based on annual data from Swedish counties, the evaluation found that between 1986 and 2001 public transport fares exceeded the passenger-maximising fare most of the time in all but two counties, the average deviation being 1-215%. Evaluating the alternative, passenger-maximising policy, including both fare and service changes for 2001, demonstrated that demand for local public transport in Swedish counties could have been increased by 0-178% without increasing subsidies. Aggregated, this represents a 2.3% increase in the number of trips on local public transport in Sweden.     

矿产资源资产估价的动态收益现值法研究

应用随机时间序列理论和资产评估理论对矿产资源资产估价的收益现值法进行了研究,建立了待估矿产资源资产未来净收益的动态预测模型,提出了折现率历史数据的测算方法,据此,建立了与净收益预测模型相类似的未来折现率的动态预测模型。这些模型和方法为把现行的偏重于静态的收益现值法扩展为科学实用的动态收益现值法奠定了基础。