Random regret minimization or random utility maximization: an exploratory analysis in the context of automobile fuel choice

Interest in alternative behavioural paradigms to random utility maximization (RUM) has existed ever since the dominance of the RUM formulation. One alternative is known as random regret minimization (RRM), which suggests that when choosing between alternatives, decision makers aim to minimize anticipated regret. Although the idea of regret is not new, its incorporation into the same discrete choice framework of RUM is very recent. This paper is the first to apply the RRM‐model framework to model choice amongst durable goods. Specifically, we estimate and compare the RRM and RUM models in a stated choice context of choosing amongst vehicles fuelled with petrol, diesel and hybrid (associated with specific levels of fuel efficiency and engine capacity). The RRM model is found to achieve a marginally better fit (using a non‐nested test of differences) than its equally parsimonious RUM counterpart. As a second contribution, we derive a formulation for regret‐based elasticities and compare utility‐based and regret‐based elasticities in the context of stated vehicle type choices. We find that in the context of our choice data, mean estimates of elasticities are different for many of the attributes and alternatives. Copyright © 2011 John Wiley & Sons, Ltd.     

Investigation of regenerative and Anti-lock Braking interaction

The use of a regenerative braking mode can reduce overall vehicle energy usage for most of the most common drive cycles. However, a number of technical issues restrict the use of regenerative braking for all possible braking situations. These issues are concerned with two key limitations. The first is related to physical limitations of the applied regenerative braking system, e.g. Electric Motor (E-Motor) power limits; energy storage device capacity and vehicle load transfer etc. The second limitation results from the potentially detrimental interaction between regenerative braking and the Anti-locking Braking System (ABS). The first type of limitation can, to some extent, be alleviated by suitable choice of hardware and, as a consequence, will not be discussed further in this paper. The second type of limitation concerns the regenerative braking strategies during an ABS event. Some of the regenerative braking strategies designed and investigated within the Low Carbon Vehicle Technology Project (LCVTP) will be described and analyzed in this paper. A comparison of competing strategies is made and conclusions are drawn together with suggestions for further research. The work has been progressed as a part of a major research programme; namely the LCVTP, which has been conducted within an extensive industrial and academic partnership, mutually funded by the European Regional Development Found and Advantage West Midlands.     

Pooling for the journey to work: The outlook in Great Britain

Pooling, or ride-sharing, is a term coined in the United States (U.S.) to describe various forms of collective travel organised for, and often by, specific groups of commuters with similar travel requirements. Its different forms include bus pooling (financially self-supporting works bus or commuter coach services), minibus pooling (van pooling in U.S. terminology) and car pooling. It has been claimed that these forms of collective travel offer a more personalised service than conventional stage carriage buses, and therefore have a greater chance of attracting solo car drivers and increasing vehicle occupancies. This, in turn, can lead to lower fuel consumption and reduced traffic congestion at peak times. Following the advent of oil shortages in the winter of 1973/74, considerable efforts were made in the U.S. to promote pooling initiatives. This gave rise to the publication of a substantial volume of literature that sometimes indicated significant resource-saving achievements. This paper considers the potential for bus, minibus and car pooling in Great Britain, drawing both on relevant theoretical and economic studies, and on practical operational experience. It concludes that under reasonable assumptions about the transport situation in the next decade or so, pooling could become increasingly useful for solving the travel problems of individual local groups, but that it is unlikely to become a major mode in terms of the numbers of trips carried. The effects of recent legislative changes are discussed, and the justification for further change assessed. Relevant comparisons are made with the U.S.Crown Copyright 1983. Extracts from the text may be reproduced, except for commercial purposes, provided the source is acknowledged.     

An Evaluation of Passive Automotive Suspension Systems with Variable Stiffness and Damping Parameters

Passenger discomfort, suspension working space and dynamic tyre loading parameters are calculated for different combinations of spring stiffness and damping coefficient representing the suspension system in a quarter car model subject to realistic random disturbance inputs from roads of widely differing quality. Sprung and unsprung masses and the tyre vertical stiffness and damping coefficient employed derive from a current production car. Designs which are best for the specific conditions represented are identified and their performance properties in other (off-design) conditions are considered, and conventional design is explained as the inevitable consequence of the need to compromise if fixed suspension parameters are used. Performance improvements possible if variable parameters can be employed are evaluated as a function of the ranges of variability provided, and a stratagem for controlling parameters is proposed.     

Ultimate strength design of stiffened plates under axial compression and bending

The basis for design of stiffened plates under longitudinal compression is outlined and predictions using several codes are compared against numerical results from an inelastic beam-column formulation and test results. In order to explore the inherent differences in column behaviour separately from discrepancies arising due to plate panel behaviour, the code predictions are re-evaluated adopting a common plate panel effective width formulation. On this basis, a critical review of code methods is made and some modifications are proposed.

The effect of the magnitude and direction of applied uniform bending on the axial capacity of stiffened plates is investigated by comparing two alternative design approaches, namely an interaction equation and a method based on the Perry equation, against results from numerical analyses and from rigid plastic theory. The interaction equation is invariably more conservative than the Perry approach but its simplicity tends to be convenient for routine design applications. Finally, results of numerical analyses, together with experimental results from previous studies, on continuous stiffened plates under combined axial compression and lateral pressure are presented and available design guidance is discussed.     

Productive efficiency and ownership of urban bus services

The established ownership mix of urban bus operations in Australia provides a unique opportunity to investigate the productivity differences between public and private bus service supply. Using duality theory in economics which links economic indices of factor productivity to the cost structure of a firm, we develop empirical measures of total and partial productivity of inputs, and adjust the differences for the effects of ownership status and operating environment. The evidence supports the notion that private supply of public passenger transport in general has performed more efficiently in the past than public supply, although the differences in productivity need not continue in the future.     

为英国市场提供的改进型电动车组Desiro UK

Siemens公司为英国铁路区间交通开发了能适应当地各种不同需要的动车组家族Desiro UK.动车组设计考虑了两种不同的电流制、不同的车辆和列车长度以及端车的两种不同车头形式.主要影响牵引设备和车辆控制设计的准入程序是一特殊的挑战.     

Modeling and Dynamics of Friction Wedge Dampers in Railroad Freight Trucks

A mechanical model for the vertical response of the bolster and friction-wedge suspension elements in a railroad freight truck is developed. The model incorporates linear stiffnesses and dry friction contact between rigid elements. Numerical bifurcation diagrams for sticking events, obtained for parameterizations of the amplitude and frequency of a harmonic track excitation, and for various friction laws, reveal distinct parameter-dependent dynamic responses: strongly nonlinear stick-slip oscillations, observed away from period-1 resonance; and weakly nonlinear, nearly harmonic responses, observed near the period-one resonance. The analytical method of harmonic balance is applied to develop a first order approximation for the period-1 response, and, as should be expected, is found to correspond well with the numerical results in the large amplitude limit and near the resonance location. Given that such weakly nonlinear, large amplitude, period-1 responses are not common for the speeds and system parameters of most freight vehicles, we conclude that friction-wedge models based on some form of equivalent linearization may be inadequate for simulating freight car dynamics in many cases of practical importance.     

Theoretical Analysis of a Semi Active Suspension Fitted to an Off-Road Vehicle

A theoretical analysis is presented to model a hydromechanical, semi-active suspension system, first as a single wheel station and then as fitted to each wheel of an off-road vehicle. Predicted results show that two benefits are obtained by comparison with the equivalent passive system. First, vehicle attitude is controlled for changes in body forces arising from static loads or braking/cornering inputs. Second, a significant improvement in ride comfort is obtained because low suspension stiffnesses can be used.