20,651 research outputs found

    On green routing and scheduling problem

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    The vehicle routing and scheduling problem has been studied with much interest within the last four decades. In this paper, some of the existing literature dealing with routing and scheduling problems with environmental issues is reviewed, and a description is provided of the problems that have been investigated and how they are treated using combinatorial optimization tools

    Spatial Analysis of Travel Demand and Accessibility in Vermont: Where will EVs work?

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    The suitability and charging requirements of electric vehicles (EVs) may differ in rural areas, where the electrical grid may be less robust and daily VMT higher. Although other studies have examined issues of regional power requirements of EVs, none have done so in conjunction with the spatial considerations of travel demand and accessibility. We use three datasets to forecast the future spatial distribution of EVs, as well as to assess these vehicles’ ability to meet current daily travel demand: the National Household Travel Survey (NHTS), geocoded Vermont vehicle fleet data, and an E911 geocoded dataset of every building statewide. We consider spatial patterns in existing daily travel and homebased tours to consider EV charging locations, as well as area-types that are unsuited for widespread electric vehicle adoption. We also consider how built environment attributes, including residential and commercial density and retail accessibility, affect travel demand and thus future EV energy requirements. We found that existing hybrid vehicles were more likely to be located near other hybrids than conventional vehicles were. This clustering of current hybrid vehicles, in both urban and rural areas, suggests that the distribution of future EVs may also be clustered. Our analysis suggests that between 69 and 84% of the state’s vehicles could be replaced by a 40-mile range EV, and 96-99% could be replaced by a 100-mile EV, depending on the availability of workplace charging. We did not find a strong relationship between land-use and travel demand, perhaps due to our low number of urban data points, the highly variable nature of rural travel, and the limitations of using a one-day travel log dataset. Our results suggest EVs are a viable option to serve existing travel demand by rural residents but may require special consideration for power supply and vehicle charging infrastructure

    Unique Opportunities of Island States to Transition to a Low-Carbon Mobility System

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    Small islands developing states (SIDS) contribute minuscule proportions to global greenhouse gas (GHG) emissions and energy consumption, but are highly exposed to climate change impacts, in particular to extreme weather events and sea-level rise. However, there is little research on potential decarbonization trajectories unique to SIDS. Here, we argue that insular topology, scale, and economy are distinctive characteristics of SIDS that facilitate overcoming carbon lock-in. We investigate these dimensions for the three islands of Barbados, Fiji, and Mauritius. We find that insular topologies and small scale offer an opportunity for both public transit corridors and rapid electrification of car fleets. The tourism sector enables local decision-makers and investors to experiment with shared mobility and to induce spillover effects by educating tourists about new mobility options. Limited network effects, and the particular economy thus enables to overcome carbon lock-in. We call for targeted investments into SIDS to transition insular mobility systems towards zero carbon in 2040. The decarbonization of SIDS is not only needed as a mitigation effort, but also as a strong signal to the global community underlining that a zero-carbon future is possible.DFG, 414044773, Open Access Publizieren 2019 - 2020 / Technische UniversitÀt Berli

    Unsplittable Load Balancing in a Network of Charging Stations Under QoS Guarantees

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    The operation of the power grid is becoming more stressed, due to the addition of new large loads represented by Electric Vehicles (EVs) and a more intermittent supply due to the incorporation of renewable sources. As a consequence, the coordination and control of projected EV demand in a network of fast charging stations becomes a critical and challenging problem. In this paper, we introduce a game theoretic based decentralized control mechanism to alleviate negative impacts from the EV demand. The proposed mechanism takes into consideration the non-uniform spatial distribution of EVs that induces uneven power demand at each charging facility, and aims to: (i) avoid straining grid resources by offering price incentives so that customers accept being routed to less busy stations, (ii) maximize total revenue by serving more customers with the same amount of grid resources, and (iii) provide charging service to customers with a certain level of Quality-of-Service (QoS), the latter defined as the long term customer blocking probability. We examine three scenarios of increased complexity that gradually approximate real world settings. The obtained results show that the proposed framework leads to substantial performance improvements in terms of the aforementioned goals, when compared to current state of affairs.Comment: Accepted for Publication in IEEE Transactions on Smart Gri

    E-business impacts for urban freight: results from an Australian study

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    E-Business is expected to dramatically change the way business is conducted internationally, nationally, within states and at the local area level. Moreover, these changes are very likely to happen well within the planning time frames required for provision of transport infrastructure and services. E-business is defined as including e-commerce, either between Businesses to Business (B2B) or Business to Customers (B2C), and the adoption of electronic technology within businesses. This paper presents some results from a study commissioned by the Australian National Transport Secretariat (NTS) to assist Australian business and government pro-actively address the transport issues arising from e-business. The resulting working papers will be used to establish a research framework for identifying policy and planning levers to maximize benefits to Australia from national and global e-business activity. The study sought to investigate three principal questions on e-business impacts: how will the transport task change; what will be affected; and how can the transport system respond? Current literature suggests that growth in e-business stems from the combined existence of market demand, suitable enabling technology, and skills and familiarity in management/users/ industry/government. The results of the study suggest that e-business will have implications for urban freight including higher levels of demand for goods and services, increased requirements for logistics distribution, changes in location preferences and improved transport network performance
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