Measuring the equity effects of a carbon charge on car commuters: A case study of Manchester Airport

This papers attempts to quantify the equity effect of a hypothesized economic instrument, a carbon charge on car commuters, for reducing carbon dioxide emissions produced by commuters on airport surface access. Manchester Airport is taken as a case study using staff Survey data from 2008 and 2010. Consumer welfare change is analysed for measuring the equity effects of carbon charge by user group, which considers the changes of travel mode choice, the carbon dioxide emissions reduction, the revenue from a carbon charge and how it is distributed. First, the individual carbon footprint in terms of gram passenger kilometre, and the damage cost of carbon by commuters on airport surface access are estimated. Next, the impact of carbon charge on travel behaviour is investigated by the nested logit model. Finally, the net effect of carbon charges is assessed by travel mode user, gender, job type, and age group. The results show some impacts of the carbon charge on car users and carbon reduction, and the positive effects on lower income group and less carbon commuters. The quantified results provide the evidences for the mitigation policies to combine monetary incentives with disincentives for travel behaviour change, and demonstrate the different equity effects among commuter groups.     

道路交通事故影响因素分析

分别从人、车辆、道路及管理四个方面分析了诱发交通事故的原因,提出了为减少和预防交通事故发生的措施.     

Market dynamics and indirect network effects in electric vehicle diffusion

The diffusion of electric vehicles (EVs) is studied in a two-sided market framework consisting of EVs on the one side and EV charging stations (EVCSs) on the other. A sequential game is introduced as a model for the interactions between an EVCS investor and EV consumers. A consumer chooses to purchase an EV or a conventional gasoline alternative based on the upfront costs of purchase, the future operating costs, and the availability of charging stations. The investor, on the other hand, maximizes his profit by deciding whether to build charging facilities at a set of potential EVCS sites or to defer his investments.The solution of the sequential game characterizes the EV-EVCS market equilibrium. The market solution is compared with that of a social planner who invests in EVCSs with the goal of maximizing the social welfare. It is shown that the market solution underinvests EVCSs, leading to slower EV diffusion. The effects of subsidies for EV purchase and EVCSs are also considered.     

Glacial ice impacts: Part I: Wave-driven motion and small glacial ice feature impacts

Glacial ice features in the northern and central Barents Sea may threaten ships and offshore structures. Particularly, small glacial ice features, which are difficult to detect and manage by concurrent technologies, are of concern. Additionally, small glacial ice features are more susceptible to wave-driven oscillatory motions, which increases their pre-impact kinetic energy and may damage ships and offshore structures. This paper is part of three related papers. An initial paper (Monteban et al., 2020) studied glacial ice features’ drift, size distribution and encounter frequencies with an offshore structure in the Barents Sea. The following two papers (Paper I and Paper II) further performed glacial ice impact studies, including impact motion analysis (Paper I) and structural damage assessment (Paper II). This paper (Paper I) studies the wave-driven motion of small glacial ice features and their subsequent impact with a given offshore structure. The aim here is to develop a numerical model that is capable of efficiently calculating the relative motion between the ice feature and structure and to sample a sufficient amount of impact events from which statistical information can be obtained. The statistical information entails the distributions of the impact location and associated impact velocities. Given the distributions of the impact velocities at different locations, we can quantify the kinetic energy for related impact scenarios for a further structural damage assessment in Paper II (Yu et al., 2020).In Paper I, a numerical model that separately calculates the wave-driven oscillatory motion and the mean drift motion of small glacial ice features is proposed, implemented and validated. Practical and fit-for-purpose hydrodynamic simplifications are made to simulate and sample sufficient impact events. The numerical model has been favourably validated against existing numerical results and experimental data. A case study is presented where a 10 m wide glacial ice feature is drifting under the influence of surface waves towards an offshore structure. The case study shows that if an impact happens, the overall impact location and impact velocity can be best fitted by the Normal and Weibull distributions, respectively. Additionally, the impact velocity increases with impact height. Moreover, the impact velocity increases and the impact range is more dispersed in a higher sea state. It is also important to notice that the approaches and methods proposed in this paper adhere to and reflect the general requirements stated in ISO19906 (2019) and NORSOK N-003 (2017) for estimating the design kinetic energy for glacial ice impacts.     

From willingness to action: Do push-pull-mooring factors matter for shifting to green transportation?

Motivating individuals to choose green transportation is becoming increasingly important. Based on push-pull-mooring framework, this study aims to explore how push, pull and mooring factors foster individual’s willingness to shift to green transportation. This study also analyzes the role of information provision in narrowing the gap between shifting willingness and behavior. The findings revealed that push factors, including perceived environmental threats and perceived inconvenience, drive individual’s mode-shift away from private cars, whereas the pull factors, including green transport policies and campaigns, and green transport system attract individual’s mode-shift to green transportation. Moreover, the mooring factor, namely inertia, not only negatively affects individual’s shifting willingness but also negatively moderates the effects of push and pull factors on individual’s shifting willingness. In addition, shifting willingness positively affects the shifting behavior and the information provision positively moderates the relationship among them. Such findings are vital to achieve the realization of China’s low-carbon goals.     

Investigation on the nonlinear effects of the vertical motions and vertical bending moment for a wave-piercing tumblehome vessel based on a hydro-elastic segmented model test

Although the nonlinear effects of the ship motions, wave-induced loads and structural responses of conventional vessels have been investigated experimentally and numerically in recent years, similar studies on the wave-piercing tumblehome (WPTH) vessels are rare, in spite of the urgent necessary due to their extensive applications. This paper experimentally investigated the nonlinear effects of the vertical motions and vertical bending moment (VBM) for a WPTH vessel based on a hydro-elastic segmented model test. The model test was carried out in head regular waves for three amplitudes, in the towing tank at Harbin Engineering University. Based on the band-pass filter technique, four kinds of decomposed harmonics are defined by mean offset, linear wave-frequency response, nonlinear wave-frequency response and nonlinear high-frequency vibration. Meanwhile, based on mean offset, three kinds of combined responses are defined by considering linear wave-frequency response, nonlinear wave-frequency response and nonlinear high-frequency vibrations step by step. The transfer functions of vertical motions and VBM are presented as function of the incident wave frequency, and the measured data and VBM were compared with numerical calculations for validation. With the method proposed above, the results of VBM are analyzed by focusing on the influences of decomposed harmonics on the amplitudes and asymmetry of combined responses. Strong nonlinear effects are observed in the VBM. The nonlinearity of VBM can be identified by the significant amplitudes of decomposed harmonics, variation of amplitude with the wave amplitude and remarkable asymmetry about the zero axis. The hogging VBM of WPTH vessel can be even larger than the sagging VBM, which is in contrast to the general experiences from conventional vessels. Combined the calculated relative motion with the decomposed and combined histories of VBM, the occurrence of the transient impact and its characteristics are discussed, and these are then used to analyze the unconventional asymmetry of VBM. Furthermore, the influences of the bow shape over the vertical motions and VBM are discussed. At the end of the paper, the uncertainties in the test are provided.     

大跨度桥梁主梁涡激振动影响因素研究进展

现代大跨桥梁跨度更大、结构更轻柔、自振频率较低且密集,在较低风速下主梁易发生涡激振动现象。涡激振动是一种带有自激、自限特性的非线性振动,影响涡激振动响应的因素较多如雷诺数效应、紊流特性及主梁断面形式等。介绍了近期大跨度桥梁主梁涡激振动影响因素的研究进展,为抗风设计及抑振措施提供参考。     

Specification and estimation of a spatially and temporally autocorrelated seemingly unrelated regression model: application to crash rates in China

In transportation studies, variables of interest are often influenced by similar factors and have correlated latent terms (errors). In such cases, a seemingly unrelated regression (SUR) model is normally used. However, most studies ignore the potential temporal and spatial autocorrelations across observations, which may lead to inaccurate conclusions. In contrast, the SUR model proposed in this study also considers these correlations, making the model more behaviorally convincing and applicable to circumstances where a three-dimensional correlation exists, across time, space, and equations. An example of crash rates in Chinese cities is used. The results show that incorporation of spatial and temporal effects significantly improves the model. Moreover, investment in transportation infrastructure is estimated to have statistically significant effects on reducing severe crash rates, but with an elasticity of only −0.078. It is also observed that, while vehicle ownership is associated with higher per capita crash rates, elasticities for severe and non-severe crashes are just 0.13 and 0.18, respectively; much lower than one. The techniques illustrated in this study should contribute to future studies requiring multiple equations in the presence of temporal and spatial effects.

江苏LNG码头海域动力条件和冲淤变化特点

重点介绍江苏LNG码头的现状和附近海域的动力条件,通过对工程海区数年间多次水下地形测量成果的对比分析,探讨江苏LNG码头建设以来所在海区的水下地形冲淤变化的特点、影响因素和可能的发展趋势,分析海域动力环境和水下地形冲淤变化对LNG船舶进、出港及码头靠泊作业的影响,并提出应对措施的建议。     

用密栅云纹实验解析法研究方板对角拉伸的起皱过程

本文采用密栅云纹实验解析法研究方板对角拉伸的起皱过程，得到了在起皱临界状态下的位移，应变和应力的全场的瞬间和连续变化信息。发现了起皱是局部的塑性失稳现象，它与横向压力分布的区域性和区域不均匀性直接相关，它可为研究大型覆盖件成形缺陷机理开辟一条新的途径。