Ship Scheduling And Speed Optimizing In Tramp Shipping

Ship scheduling is an important problem of transportation capacity optimization and allocation in tramp shipping, and it affects economic benefit of a ship and overall profits of an enterprise directly. Speed optimization is one of key decisions that ship scheduling involves, because it decides voyage variable cost and ship utilization. Shipping companies are confronted with facts of shipping market downturn and high fuel price. Studying ship scheduling and speed optimization is beneficial for shipping companies to control fuel cost, deploy fleet reasonably and improve operation performance, meanwhile it is of great significant for maritime system in light of saving energy source and reducing emission.After summarizing and analyzing research on speed optimization, ship scheduling and other related areas, they are found that existing speed optimization methods do not consider transportation time requirements in voyage charter contracts; ship scheduling and speed optimization problem referring a lot of ships, ports, cargoes and sailing lanes is not well addressed; there is no research about ship scheduling and speed optimization problem considering demand changes. On these issues, this paper carried out the following studies:1A nonlinear programming model is proposed after considering time requirements for loading and discharging cargoes in voyage charter contracts, to solve speed optimization problem along a sailing lanes with multiple ports and cargoes. Voyage costs and benefits are estimates and optimal speed is selected simultaneously. Based on structural features of the model, apply exterior point method and pattern search algorithm to resolve it.2Analyze the impact of cruise speed on sailing time and fuel costs, the impact of actual amount of cargo on freight revenue, transportation cost and loading/unloading time comprehensively, then establish a ship scheduling and speed optimization model with flexible cargo size to select and allocate cargoes, plan routes for ships, deploy ships and optimize speed simultaneously. A two-phase algorithm based on set partitioning is design to decompose and simply the large-scale nonlinear mixed integer programming problem. The first phase is to contract all the feasible schedule of the fleet though enumeration tree,0-1matrix of sailing lane and resolving small-scale nonlinear programming models with same structure. Optimal ship schemes are selected by set partition approach to maximize overall revenues of the fleet. Experiments with different scale are carried out to analysis and examine impact of ship speed and flexible cargo size on the overall revenues and ship schedules.3Ship scheduling and speed optimization problem considering demand changes is proposed and studied. The problem is sorted into four types:the fixed original route and a single cargo, the fixed original route and several cargoes, the variable original route and a single cargo, the variable original route and several cargoes. Take systematic analysis and classification optimization thinking to address the problem. Nonlinear programming models are established and solution methods are developed for the problems of different types.