Exploring spatial variety in patterns of activity-travel behaviour: initial results from the Toronto Travel-Activity Panel Survey (TTAPS)

Studies of urban travel behaviour typically focus on weekday activities and commuting. This is surprising given the rising contribution of discretionary activities to daily travel that has occurred during the last few decades. Moreover, current understanding of the relationship between travel behaviour and land use remains incomplete, with little research carried out to explore spatial properties of activity-travel behaviour during the off-peak and weekend time periods. Weekend behaviours, for example, influenced by the availability of time and the spatiotemporal distribution of “weekend” destinations, likely produce spatially and temporally distinct activity-travel patterns. Using data from the first wave of the Toronto Travel-Activity Panel Survey (TTAPS), this paper examines an area of research that has received little attention; namely, the presence of spatial variety in activity-travel behaviour. The paper begins by looking at the extent to which individuals engage in spatially repetitive location choices during the course of a single week. Area-based measures of geographical extent and activity dispersion are then used to expose differences in weekday-to-weekend and day-to-day activity-travel patterns. Examination of unclassified activities carried out over a 1 week period reveals a level of spatial repetition that does not materialise across activities classified by type, travel mode, and planning strategy. Despite the inherent spatial flexibility offered by the personal automobile, spatial repetition is also found to be surprisingly similar across travel modes. The results also indicate weekday-to-weekend, and day-to-day fluctuations in spatial properties of individual activity-travel behaviour. These findings challenge the utility of the short-run survey as an instrument for capturing archetypal patterns of spatial behaviour. In addition, the presence of a weekday-to-weekend differential in spatial behaviour suggests that policies targeting weekday travel reduction could have little impact on travel associated with weekend activities.

Maritime interests in the EU policy-making: Structures,practices, and governability of collective action

Throughout Europe, a number of maritime interests have re-targeted their lobbying structures and strategies aiming to influence the development of the maritime related European Union (EU) policies. The paper examines these maritime interests’ mobilisation in the making of the Common EU Maritime Transport Policy (CMTP). First, it provides a review of the role of these interest groups and the implications of the observed collective interests’ representation. Then, with the contribution a data-set of replies to a questionnaire distributed to all the interest groups that are involved in EU maritime affairs, the paper analyses the variety of interest groups representing the maritime sector in EU affairs. The focus is on the structures (i.e. membership numbers and types, location, internal structures, budget) and the lobbying practices of the 37 identified EU level maritime related organisations. The paper also presents an evaluation of the most positive and most negative parameters of the ‘EU environment’ and the ‘economic environment’ that assist, or undermine, the governability cohesiveness of this collective action. This study provides information on whether and under what conditions maritime interests are able to form comprehensive EU-level organisations capable of representing their members and their interests in the EU policy making process     

An approach to estimating the hull girder response of a ship due to springing

This article describes an estimation method for the hull girder response of a ship due to springing. The linear and nonlinear springing effects on the hull girder are evaluated. Previous studies on the springing response focused mainly on the symmetric response, or vertical response. In this article, however, the springing analysis is extended to asymmetric responses, or horizontal and torsional responses. The Timoshenko beam model was used to calculate the hull girder response and the quadratic strip method was employed to calculate hydrodynamic forces and moments on the hull. To remove irregular frequencies, a rigid lid was adopted on the hull free surface level and hydrodynamic coefficients were interpolated for asymptotic values. Applications to two ships for the symmetric and asymmetric responses were carried out and the effect of springing responses is also discussed.     

A chance-constrained based stochastic dynamic traffic assignment model: Analysis, formulation and solution algorithms

This paper is concerned with the system optimum-dynamic traffic assignment (SO-DTA) problem when the time-dependent demands are random variables with known probability distributions. The model is a stochastic extension of a deterministic linear programming formulation for SO-DTA introduced by Ziliaskopoulos (Ziliaskopoulos, A.K., 2000. A linear programming model for the single destination system optimum dynamic traffic assignment problem, Transportation Science, 34, 1–12). The proposed formulation is chance-constrained based and we demonstrate that it provides a robust SO solution with a user specified level of reliability. The model provides numerous insights and can be a useful tool in producing robust control and management strategies that account for uncertainty in applications where SO-DTA is relevant (e.g. evacuation modeling, computing alternate routes around freeway incidents and establishing lower bounds on network performance).     

底部薄板附近的水流及泥沙运动特性

通过水槽实验探讨了在饱和来沙条件下底部薄板附近的水流、泥沙运动特性,包括不同薄板高度、与水流不同夹角的安装方向等情况下,单个底部薄板附近的水流结构、泥沙运动规律、底部薄板的导沙特性及其附近的冲淤现象,以及底部薄板群体的导沙特性。试验结果表明,实验使用的薄板的长度对实验结果影响很大,过短的薄板实验根本观察不到薄板前冲刷沟内的沙波运动,而该沙波运动严重影响薄板的导沙效应。底部薄板附近的水流结构具有强烈的三维特性,流场复杂,对于一定的薄板,水流夹角、沙波的运动是影响薄板的导流导沙促淤的主要因素。     

Trading strategies in the market for tankers

This paper introduces a new approach in timing the sale and purchase of ships in the tanker market and examines the performance of this trading strategy over the period January 1976 to September 2004. Based on the long-run cointegration relationship between earnings and price, we establish a trading model which can be used as an indicator of investment or divestment timing decisions. We also perform statistical tests using the bootstrap approach in order to discount the possibility of data snooping biases and test the robustness of our trading models. Our results indicate that trading strategies based on earning-price ratios significantly out-perform buy and hold strategies in the tanker market.     

Computer-Simulation of the Dynamical Curving Behaviour of a Railway-Bogie

This paper describes the modelling of a two axle railway-bogie with variable design configurations and its application in the investigation of the behaviour in transitional and circular curves. Several results indicate possibilities to improve the curving properties and recommend the usage of forced-steering bogies, which show better performance in narrow curves without unbearable sacrifices to high-speed-behaviour on straight track.