Electric vehicles, a significant part of sustainable transport, are attracting increasing attention with the development of sustainable cities. However, as supporting facilities of electric vehicles, public charging stations are of great significance to the promotion of electric vehicles. This paper proposes an electric vehicle charging station location model to improve the resource utilization of electric vehicles for sustainable cities. In this model, reservation services, idle rates during off-peak periods, and waiting time during peak periods are considered. Finally, a case from Chengdu, China, is used to examine the effectiveness of the proposed model. Then, further analyses of reservation ratios and penetration rates are conducted. The results show that the introduction of a reservation service has a positive effect on reducing the total cost, which would provide further support for sustainable cities and have an even greater impact on healthier lives.
2 March 2024 in Separation and Purification Technology
To address the protracted blood transportation time prevalent in contemporary urban settings, we proposed a location-routing optimization problem tailored to the distribution of blood within intricate road networks. This involved a comprehensive assessment that encompassed the judicious selection of sites for both stations and blood centers, coupled with the meticulous planning of delivery routes for unmanned aerial vehicles (UAVs) that orchestrate the transportation of blood. First, a model was formulated to minimize the overall cost, including transportation expenses, costs associated with the site, and other relevant costs related to blood transportation vehicles coordinated by UAVs. Subsequently, a two-stage hybrid heuristic algorithm was designed based on the distinctive characteristics of the problem at hand. Moreover, an enhanced k-means algorithm was employed to generate clustering schemes, utilizing the centroid method to address the challenge of location selection for delivery sites effectively. A genetic algorithm enhanced with adaptive operators was employed to address the challenging large-scale NP-hard problem associated with route planning in intricate urban road networks. The results indicated that, compared to the traditional blood delivery model using vehicles, the total blood transportation cost decreased by 12.65% and the overall delivery time was reduced by 37.5% with the adoption of drone-assisted delivery; ultimately, case and sensitivity analyses were conducted to investigate the impact of variables including the number of blood transportation vehicles, UAVs, driver wages, and unit costs of blood transportation vehicles on the location-routing problem.
8 June 2022 in Journal of Air Transport Management
In the past few years, drones have been adopted as a novel delivery tool towards medical supplies, improving delivery service efficiency due to fast speed and neglection of geographical limitations. However, the flight endurance of a battery‐operated drone is limited for long‐distance medical supplies delivery operations. Recharging stations, as a kind of drone facility, allow multiple stops for drones to supplement the power to overcome the flight‐range limitations. This paper studies drone‐assisted long‐distance medical supplies delivery with recharging stations in rural communities by a mixed integer linear programming model. To illustrate the applicability of this model and explore the key factors influencing delivery efficiency of medical supplies, a case study from China is conducted. The results indicate that enhancements on the speed of a truck or a drone can yield considerable delivery cost reduction. In addition, drone‐recharging technology advances can improve delivery efficiency of medical supplies in rural communities.