轿车人体坐姿校核分析研究

通过研究人体尺寸与汽车内部空间的关系及近似车型的舒适人体坐姿,并根据设计车型的空间综合考虑,得出设计人体坐姿,并可根据参考车型评价其舒适程度。     

Experiences with Competitive Tendering of Bus Services in Germany

Abstract

After a long transition period with only a few isolated procedures for competitive tendering, the market for German public transport bus services has seen numerous such tenders in recent years. The results are complex. From the public transport authorities’ point of view, the main effects are a decrease in subsidy payments, with relatively low expenses relating to the tendering process (allocation, contract management). The overall level of competition is high, with five to seven bidders on average, although this has been declining in recent years. Entry barriers have been identified at significant levels for several parameters, especially with respect to the volume tendered and the revenue risk to be borne by the operator out of net‐cost contracts. Demonstrably small‐ and medium‐sized transport operators have been able to increase their market share in the starting phase of introducing tendering, with diminishing success rates in recent years. Due to the increased quality requirements in competitive tendering, the quality of public transport available has improved considerably, and environmental standards have been better implemented and sustained. As far as employees are concerned, a trend towards wages below the wage rate of private operators cannot be observed. However, their level is well below the level of public incumbent operators.     

Examining pedestrian-injury severity using alternative disaggregate models

This paper investigates the injury severity of pedestrians considering detailed road user characteristics and alternative model specification using a high-quality Danish road accident data. Such detailed and alternative modeling approach helps to assess the sensitivity of empirical inferences to the choice of these models.     

From theory to practice in road safety policy: Understanding risk versus mobility

This paper reviews theoretical issues surrounding transport safety modeling and the implications for road safety policy. The behavioral mechanisms that affect transport safety are typically not considered in safety modeling. These issues are discussed in the context of trade-offs between risk-taking, as perceived by travelers, and other mobility objectives and the attributes associated with them. This is an extension of other theoretical frameworks, such as risk compensation, and attempts to integrate some of the previous frameworks developed over the years. Various examples of behavioral adaptation to specific policies are discussed and linked to the framework. These issues are then discussed in the context of improvements to empirical work in this area and the linkage of theoretical frameworks to crash modeling, in particular the estimation and use of Crash Modification Factors. Conclusions suggest that there are many deficiencies in practice, from estimation of models to choice of effective policies. Progress is being made on the former, while the publication of practical guidance seems to have substantial lags in knowledge.     

Estimating demand variables of maritime container transport: An aggregate procedure for the Mediterranean area

Demand variables of maritime container transport (throughput, transhipment and origin–destination flows) may be estimated with freight demand models. As their parameters generally vary both in time and space, models may not be transferable to geographical areas and time periods differing from that for which they are calibrated.     

Strategies of state and local government in management of urban transport problems – A case of Delhi

In India, different layers of Government control different policy instruments to tackle transport externalities which might result in coordination problems and possible efficiency losses. This paper, therefore, addresses the coordination problem resulting from the division of policy instruments between two different government levels that face different types of externalities in varying degrees of magnitude in the urban transport sector by developing three types of theoretical models: the Full Control Centralised Model where the state government has full control over all pricing instrument; a Nash equilibrium model where each of the government levels controls only one instrument and takes the behaviour of the other as given; and a Stackelberg equilibrium mode where the behaviour of the state government is influenced by the fact that one of the price instruments is controlled by the local government. With an empirical illustration of the model for Delhi, the paper finds that since there are many interactions and many externalities between the two levels of government, a division of roles between them does not guarantee an efficient pricing outcome and the efficiency of pricing would depend on the institutional set up and on the correspondence between the objective functions of the two government levels.     

WC5R煤矿用防爆柴油机无轨胶轮指挥车设计

为积极响应国家政策,保障煤矿高产高效、安全生产,设计开发了WC5R煤矿用防爆柴油机无轨胶轮指挥车,介绍了其设计原理及总体结构。     

Remaining fatigue life assessment of corroded mooring chains using crack growth modelling

Failures caused by the combined actions of fatigue, corrosion and wear are important safety concerns for mooring chains used on floating structures in the oil and gas industry. Prediction of remaining corrosion fatigue life based on surface condition could therefore be a useful tool for the continued safe operation of corroded chains. This paper investigates the use of crack growth modelling for estimating the remaining corrosion fatigue life of mooring chains that exhibit significant pitting corrosion damage. A crack growth modelling approach is used to produce remaining fatigue life estimates for a selection of severely pitted mooring chains. Using fatigue crack growth rate test results for grade R4 high strength mooring chain steel, empirical crack growth laws are presented for free corrosion and cathodic protection conditions at load ratio R = 0.1. Two different methods for establishing equivalent cracks from surface scans of corrosion damage are presented. The mooring chains are proof loaded as part of their manufacturing process. Residual stresses introduced during this process have therefore been determined by finite element analysis and accounted for in the fatigue crack growth predictions. One of the equivalent crack models, accounting for the single dominant corrosion pit, provided quite accurate fatigue life predictions when compared with full scale test results.