Abstract

Evaluating potential of shifting to low-carbon transport modes requires considering limited travel-time budget of travelers. Despite previous studies focusing on time-relevant modal shift, there is a lack of integrated and transferable computational frameworks, which would use emerging smartphone-based high-resolution longitudinal travel datasets. This research explains and illustrates a computational framework for this purpose. The proposed framework compares observed trips with computed alternative trips and estimates the extent to which alternatives could reduce carbon emission without a significant increase in travel time.. The framework estimates potential of substituting observed car and public-transport trips with lower-carbon modes, evaluating parameters per individual traveler as well as for the whole city, from a set of temporal and spatial viewpoints. The illustrated parameters include the size and distribution of modal shifts, emission savings, and increased active-travel growth, as clustered by target mode, departure time, trip distance, and spatial coverage throughout the city. Parameters are also evaluated based on the frequently repeated trips. We evaluate usefulness of the method by analyzing door-to-door trips of a few hundred travelers, collected from smartphone traces in the Helsinki metropolitan area, Finland, during several months. The experiment’s preliminary results show that, for instance, on average, 20% of frequent car trips of each traveler have a low-carbon alternative, and if the preferred alternatives are chosen, about 8% of the carbon emissions could be saved. In addition, it is seen that the spatial potential of bike as an alternative is much more sporadic throughout the city compared to that of bus, which has relatively more trips from/to city center. With few changes, the method would be applicable to other cities, bringing possibly different quantitative results. In particular, having more thorough data from large number of participants could provide implications for transportation researchers and planners to identify groups or areas for promoting mode shift. Finally, we discuss the limitations and lessons learned, highlighting future research directions. Document type: Article

Abstract

The dynamic load in tubes due to detonation has a number of applications, such as in oil pipeline systems and pulse detonation engines. Various experimental, analytical, and numerical investigations have been conducted to study the mechanical, thermo-mechanical, and fracture behavior of tubes under internal detonation loads. Regarding numerical analysis, different approaches such as interface cohesive element, mesh-free, and extended finite element methods have been used to model the propagation of crack(s) in a tube. This paper presents a review of relevant literature pertaining to numerical and experimental analyses of detonation-driven deformation and fracture, and of studies based on the analytical investigation of moving loads in detonation tubes. The corresponding findings are discussed in detail, and possible avenues for future research are highlighted. Peer reviewed