Ride Dynamics of Articulated Vehicles-A Literature Survey

This paper presents a review of the available literature describing the methods of modelling the vibrational response of articulated vehicles to the road inputs at the tire contact points. It states and discusses the mathematical techniques that have been put forward for obtaining road input characteristics, for modelling the vehicles in a range of degrees of freedom, and for performing the analysis necessary to obtain the vibrational response. Finally the indices that have been proposed for ride comfort and ride safety are given and the manner in which various researchers relate these to the vibrational characteristics of the vehicles is described.     

Analytical Tire Models for Dynamic Vehicle Simulation

Four basic tire models suitable for dynamic vehicle simulation are formulated. The models are compared through a six-degree-of-freedom nonlinear simulation of a cargo truck crossing rough ground. Guidelines are developed for the selection of an optimum tire model for a given dynamic vehicle simulation.     

Freight transport demand revisited: A microeconomic view of multimodal, multicharacteristic service uncertainty and the demand for freight transport

This paper provides a unifying framework for micro-based models of freight transport demand. An expected utility of profits model is posed that clarifies the conditions under which a system of equations (continuous) regression model should be used as opposed to the conditions that make a quantal choice model appropriate. The model also indicates the nature of subjective data that is necessary for estimating demand. In general, the conditions that give rise to the appropriate use of a quantal choice model imply that the needed subjective information is completely contained in the subjective probability distributions on the service characteristics; the utility function itself is irrelevant.     

The valuation of commuter travel time savings for car drivers: evaluating alternative model specifications

The empirical valuation of travel time savings is a derivative of the ratio of parameter estimates in a discrete choice model. The most common formulation (multinomial logit) imposes strong restrictions on the profile of the unobserved influences on choice as represented by the random component of a preference function. As we progress our ability to relax these restrictions we open up opportunities to benchmark the values derived from simple (albeit relatively restrictive) models. In this paper we contrast the values of travel time savings derived from multinomial logit and alternative specifications of mixed (or random parameter) logit models. The empirical setting is urban car commuting in six locations in New Zealand. The evidence suggests that less restrictive choice model specifications tend to produce higher estimates of values of time savings compared to the multinomial logit model; however the degree of under-estimation of multinomial logit remains quite variable, depending on the context.     

Hydrodynamic characteristics of slotted breakwaters under regular waves

The performance of a slotted breakwater consisting of one row of vertical slots was investigated theoretically and experimentally under normal regular waves. A simple theoretical model based on an eigenfunction was developed. The wave transmission, reflection, energy loss, and hydrodynamic force exerted on the breakwater were calculated for different values of the wave and structure parameters. The validity of the theoretical model was examined by comparing its results with theoretical and experimental results obtained from different studies. It was found that the transmission coefficient decreases with increasing dimensionless wavenumber (kh), increasing wave steepness (H _i/L), and decreasing breakwater porosity (ε). The reflection coefficient showed the opposite trend to the transmission coefficient. Also, about 20–50% of incident wave energy was lost due to the effect of the breakwater. In addition, the proposed theoretical model can be used for predicting the performance of slotted breakwaters and the hydrodynamic forces exerted on these structures using the friction coefficient f = 1.5.     

Oceanic CO2 uptake and biogeochemical variability during the formation of the Eastern North Atlantic Central water under two contrasting NAO scenarios

Long-term variability of the biogeochemical properties during the formation of central waters in the Eastern North Atlantic were analyzed between 42–47°N and 10–20°W from the dataset gathered during the Galicia VII (GVII) and C. Darwin 58/59 (CD58/59) cruises. These cruises that showed important changes in the thermohaline properties and the nutrient abundance of the upper layers were carried out under contrasting conditions of the North Atlantic Oscillation (NAO) index. The different climate forcing led a meridional shift of the transition zone between the formation regions of subpolar and subtropical Eastern North Atlantic Central Water (ENACWp and ENACWt, respectively). This displacement conditioned the presence of each ENACW in the study region and so the thermohaline and biogeochemical properties. The effect of the observed variability at decadal scale on the air–sea CO₂ gradient (ΔfCO₂) and exchange (F_CO2) was analyzed using 1D model approach throughout 11 weekly-steps that simulated the development of a spring bloom during the shoaling of the mixed layer. The outputs of the model showed an intensification of the ocean CO₂ uptake due to higher biological CO₂ drawdown, during positive NAO conditions and its weakening under negative NAO influence.     

Investigating the link between cyclist volumes and air pollution along bicycle facilities in a dense urban core

In this paper we explore the air pollution levels along types of bicycle facilities using a NO₂ land use model previously developed for Montreal. We explore potential associations between bicycle volumes through signalized intersections and pollution levels at those intersections. We further investigate this relationship through the comparison of over thirty cycling corridors as well as an evaluation of the potential exposure of cyclists to air pollution along five routes. We observe NO₂ concentrations to be positively correlated with bicycle flows at the intersection level. We also observe that corridors with either a bicycle path or cycle track generally rank higher in terms of bicycle volume and also have higher NO₂ concentrations than corridors without bicycle facilities. This indicates that intersections and bicycle facilities with a large number of cyclists are also those characterized with the highest air pollution levels.     

对停车改革认识更加清晰的停车政策分类方法

对停车政策类型缺乏广泛理解会导致对城市停车政策的混淆。通过对各地停车政策学术研究和实践应用的综述,指出以往的政策分类或缺乏完整性,过于简单、不准确,或无法洞悉差异背后的本质。并且没有一项研究能对每种停车政策及改革背后的政策思路进行分析。为弥补这些缺陷,提出一种关于停车政策新的分类方法。该方法清晰地指出不同停车改革政策背后思维模式的差异。通过回顾不同地区(国际和都市区内部地区)停车改革实践,验证分类方法的价值并提出改进措施。通过两个关键问题定义三种停车政策模式。每个模式对停车作为一种经济产品的本质提出不同的基础假设。通过第三个问题确立分类模式的第三个维度。新方法的提出能减少由于合并不同形式造成的停车争论偏好的混淆,包括假两难推理和偷换概念等关键替代形式。     

Expert versus lay perception of the risks of motor vehicle-generated air pollution

We explore whether experts’ perceptions of risk differ systematically from those of the public. To do so, we examine whether experts and non-experts make different location decisions in response to ground-level ozone pollution, one of the byproducts of motorized transportation. Physicians are experts in the field of health, and thus may differ from their lay neighbors in their knowledge of and attitude toward pollution and its health risks. If so, it is possible that they value locations with cleaner air differently than their neighbors do. Here we use hedonic price models based on willingness to bear housing and commute burdens to examine the differential valuation of clean air by doctors and laypeople in the Los Angeles region between 1980 and 2000. We find no evidence that doctors are more or less more willing than comparable lay residents to trade off time or money to live in cleaner-air neighborhoods.     

Optimal distribution of financial incentives to foster off-hour deliveries in urban areas

The main objective of this paper is to develop mathematical formulations to gain insight into the best way to distribute financial incentives to receivers of urban deliveries to maximize participation in off-hour deliveries. The paper considers two different types of incentive budgets: exogenous, and endogenous. The exogenous case represents the condition in which an external decision maker determines the incentive budget that is to be distributed among potential participants in off-hour deliveries. In the case of an endogenous incentive budget, the entity distributing the incentives must raise the necessary funds using revenue generation mechanisms such as tolls and fines. The optimal incentives are obtained from the Karush–Kuhn–Tucker conditions of a mathematical program that maximizes the number of truck trips shifted to the off-hours as a function of the incentives. The mathematical models developed in this paper provide guidelines about how to optimally distribute financial incentives to foster off-hour deliveries.