Siyi Zhuge

As electric vehicles have become increasingly popular in recent years, battery swapping technology has been promoted as an alternative to the time-consuming battery charging process. Nevertheless, battery swapping is held back by the trade-off between the additional battery investment and the short service time for users. In this paper, we developed simulation models to analyze the economics of battery swapping systems. In particular, we collected real data from eight battery swapping stations Guangzhou, China for the analysis. The results show that the service levels of the stations are reduced significantly as the number of users increases. On the other hand, economies of scale exists when implementing the battery swapping system. As the number of users increases, to maintain the same level of service level, the cost of the batteries shared by each user decreases. The analysis also suggests that, given the scale of potential users for an area, the marginal utility of increasing the number of stations will diminish. Finally, to maximize the utility and economic return of the service, we identified that there is a trade-off between the number of stations and the amount of batteries equipped in each station.

Overcapacity of seaport infrastructure has been a common issue in many countries in recent years. Cautious investment decisions shall be made on the basis of realistic capacity evaluation and productivity improvement of existing ports. However, operational analysis and evaluation of a seaport is not always easy, especially for multipurpose terminals which are commonly seen in developing countries. These small-scaled multipurpose seaports handle different cargo types with multiple interrelated processes and varying handling methods and process times. This paper studies a single-berth multipurpose seaport with wharf space restriction in Indonesia and shows how the simulation model can be essential and significantly helpful in the evaluation of the port’s productivity and realistic capacity. Furthermore, a new handling method is proposed and evaluated by the simulation model. The simulation approach and related results help the port operator in making decisions regarding port improvement and future expansion investments.