Electrified propulsion systems, such as fuel cells (FCs) and batteries, are a promising solution to decarbonize the shipping sector. In this paper, we have conducted a comprehensive analysis of two months' worth of real-world container ship power demand data. From this analysis, we propose a novel multi-time scale Energy Management System (EMS) approach for a hybrid FC/battery propulsion system. This approach enables the individual control of each FC stack while factoring in battery and FC degradation losses and fuel consumption costs. By exploring different time scales, we have assessed...
The efficient planning of stacking boxes, especially in the online setting where the sequence of item arrivals is unpredictable, remains a critical challenge in modern warehouse and logistics management. Existing solutions often address box size variations, but overlook their intrinsic and physical properties, such as density and rigidity, which are crucial for real-world applications. We use reinforcement learning (RL) to solve this problem by employing action space masking to direct the RL policy toward valid actions. Unlike previous methods that rely on heuristic stability assessments...
This paper examines the reorganization of freight transportation in the city of Venice, Italy. Most of the freight arrives from the mainland by trucks, but must be carried to the final customers by boats, through a network of small canals. The existence of constraints, related to the widths and clearances of the canals, makes it necessary to use boats of different sizes and capacities. In this paper, we analyze the transshipment operations from trucks to boats, and the organization of the boat distribution.
This paper studies the costs involved in distributing items from a warehouse or depot to randomly scattered customers on a day-to-day basis. Two trade-offs are explored simultaneously. The first one arises because by accumulating large inventories at the depot it is possible to build more efficient distribution tours. This trade-off has already been explored for both distribution of goods (Burns et al., 1983) and passengers (Daganzo et al., 1977; Hendrickson, 1978). Another tradeoff, which involves the length of individual vehicle tours (...
The object of this paper is to explain how the expected length of traveling salesman tours changes with zone shape. To do this, a simple strategy that yields good traveling salesman tours is presented. The resulting tours are suboptimal but appear to be close to those that can be obtained by hand. Thus, the formulas that are provided may also be indicative of the length of tours built with better strategies. The results of this paper are useful for the design of distribution systems.
This paper analyzes two strategies for routing shipments through transportation terminals. One strategy is to send each shipment through the terminal offering the minimum possible travel distance. The other strategy is to send each shipment through the terminal near the travel origin offering the minimum possible travel distance. Although the second strategy results in slightly larger average travel distance, more flow is consolidate onto transportation links. Flow consolidation is desirable because of economies to scale in transportation. The relation between average travel distance...
The purpose of this paper is to develop a simple formula to predict the distance traveled by fleets of vehicles in physical distribution problems involving a depot and its area of influence. Since the transportation cost of operating a break-bulk terminal (or a warehouse) is intimately related to the distance traveled, the availability of such a simple formula should facilitate the study of more complex logistics problems. A simple manual dispatching strategy intended to mimic what dispatchers do, but simple enough to admit analytical modeling is presented. Since the formulas agree rather...
