Optimisation of a multi-objective two-dimensional strip packing problem based on evolutionary algorithms

This paper considers a real-world two-dimensional strip packing problem involving specific machinery constraints and actual cutting production industry requirements. To adapt the problem to a wider range of machinery characteristics, the design objective considers the minimisation of material length and the total number of cuts for guillotinable-type patterns. The number of cuts required for the cutting process is crucial for the life of the industrial machines and is an important aspect in determining the cost and efficiency of the cutting operation. In this paper we propose the application of evolutionary algorithms to address the multi-objective problem, for which numerous approaches to its single-objective formulation exist, but for which multi-objective approaches are almost non-existent. The multi-objective evolutionary algorithms applied provide a set of solutions offering a range of trade-offs between the two objectives from which clients can choose according to their needs. By considering both the length and number of cuts, they derive solutions with wastage levels similar to most previous approximations which just seek to optimise the overall length.     

A sample average approximation approach to the berth allocation problem with uncertain tides

The remarkable increases in containerized trade over the past few years have resulted in increased congestion and operational costs of container terminals, indicating the importance of the effective management of port resources under uncertainty. In this article, a novel berth allocation model is suggested for seaports, taking into consideration the disruptive effects of tides on the berthing schedule as well as the uncertainty in the arrival time of vessels. A rigorous mathematical model is presented along with a sample average approximation method to generate an efficient berth allocation plan. In addition, statistical analysis of real data gathered from a real case is presented. Numerical analysis has been conducted to verify the practical applications of the model proposed for the berth allocation problem under uncertainty. Computational results based on a real-world data set provided by Rajaee port, Iran, demonstrate the effectiveness of the proposed solution method.