The effect of the application of advanced transport information system (ATIS) and road pricing is studied in a transportation system under non-recurrent congestion. A stochastic network deterministic user equilibrium model (SNDUE) with elastic demand is formulated and used to evaluate the welfare and private impacts of different market penetrations of ATIS, together with road pricing for a simple network. Both marginal first-best road pricing and a second-best fixed road pricing are considered. The incentives of private users to use ATIS are analyzed and the characteristics of optimum tolls as a function of ATIS market penetration are shown. We conclude that ATIS is an efficient and necessary tool to reduce the effects of non-recurrent incidents in a transportation network, especially when non-recurrent congestion causes a significant deterioration of operational conditions of the network. If the impact of non-recurrent incidents on free flow costs is small or is reduced only to congestion effects, the use of road pricing would be more efficient. Social benefits obtained when jointly implementing ATIS and road pricing are practically the same whether first-best or second-best road pricing is used. Considering the private costs perceived by the network users, and the benefits experienced by equipped users, the maximum level of market penetration achieved could be limited because private benefits disappear after certain market penetration is obtained. 相似文献
An alternative technique for identifying the transfer function of automotive suspension systems is presented in this paper. The method establishes a frequency response from which the transfer function can be determined by using a low cost test rig developed for the purpose. This results in a transfer function matrix which can include asymmetry in the suspension, tyre stiffness and damping. The technique is validated by comparing results for a two-wheeled trailer with those obtained on a conventional hydraulic test rig. Results from this procedure may be used to evaluate passive or active suspension systems or to feed into a suspension modelling process for such purposes as active suspension control strategy development. 相似文献
Risk- and reliability-based approaches are increasingly being applied in assisting inspection and maintenance planning. One of the keys to such approaches is properly predicting the hull girder strength (HG) of gradually degradated hull structures. The development has been limited by the lack of data on aging ships—validation of the developed methods has not been possible. To fill the gap of knowledge on hull strength of ships in service, this paper presents a database of as-gauged hull structures and a statistical study of the time-variant HG of tankers. The expanded data set was collected from 2195 as-gauged girth belts (transverse sections) of 211 single-hull tankers that were 12–32 years old. It was intended to (1) provide actual data on hull girder section modulus (HGSM) of tankers, (2) investigate the general trends of the change in the HG over ships’ service life, and (3) propose formulations for presenting time-variant HGSM and coating life.
The data set demonstrated a high variation of HGSM that changed over time. The mean value and standard deviation of HGSM loss were derived as functions of time. The probability density function (pdf) of coating life was also derived. Comparisons were made between previous studies on HG and the current data set. It was found that almost all previous studies showed much greater HG loss than what this database revealed. The refinement of existing calculations appears to be needed. The data set and statistical study were expected to form the basis for validating formulations of HG that are key components in risk- and reliability-based approaches. 相似文献
This paper presents a quantitative method for characterizing high speed train stations in terms of passenger intermodality. The aim of the procedure is two-fold: firstly, the method is to be used as an objective measure for comparing stations in order to detect suboptimal points and improve the performance of stations as nodal points; secondly, the method provides a means to embed intermodality into regional accessibility models, allowing comprehensive modelling at lower scales. The empirical base of the work comprises data from 27 European high speed rail stations, which is deemed an appropriate statistical sample for the whole European rail network. Using the entropy metric, we found that several different patterns emerged: there was a clear hierarchy of stations which was linked to their respective roles within the system, while strong constraints impeded stations from performing optimally as true intermodal nodes. 相似文献
The external morphology of the first three larval stages of Nucellicola holmanae is described. These stages were cultured from eggs found with the adults in the viscera of dog whelks collected from Robin Hood's Bay, North Yorkshire. The nauplius develops within the whelk. It moults to a metanauplius which is released as a free-swimming stage. The metanauplius moults to a free copepodid stage which exhibits a combination of characters typical of the first, second and third copepodid stages of other poecilostomatoid copepods. The infective copepodid stage which locates and penetrates the host is visible through the integument of this free-swimming copepodid. 相似文献
A framework for developing object-oriented software in transport modelling in proposed and demonstrated with the implementation of the calculation of road traffic noise (CORTN). Major tasks in the life cycle of an object-oriented development process are identified, and illustrated with the implementation of TRANSOOP – a software library containing 33,000 lines of C++ programming code. Software re-use from this library to produce a object-oriented noise program is compared with conventional computer programming shows that almost 90 per cent of the lines of code were drawn from TRANSOOP. Advantages of the object-oriented approach are discussed. 相似文献