Computers and Operations Research

• Most notable exact methods proposed in the literature have difficulties to optimally solve medium-sized instances.

Three-dimensional Cutting and Packing Problems consist of a set of items that must be placed inside one or more larger items (containers). Such problems enforce non-overlapping constraints which ensure that the smaller items being ...

• Scheduling a two-machine permutation flow shop to minimize earliness and tardiness is addressed

The two-machine permutation flow shop scheduling problem with the objective of minimizing total earliness and tardiness is addressed. Unforced idle time can be used to complete jobs closer to their due dates. It is shown that unforced ...

• We consider the Green Vehicle Routing Problem (G-VRP) which adapts the classical vehicle routing problem to alternative fuel vehicles.

We consider the Green Vehicle Routing Problem (G-VRP) which is an extension of the classical vehicle routing problem for alternative fuel vehicles. In the G-VRP, vehicles’ driving autonomy and possible refueling stops en-route are ...

• Studying mixed blocking flowshop scheduling problems with sequence-dependent setup times (PFSP-BS).

Permutation flowshop scheduling problem (PFSP) is a classical NP-Hard combinatorial optimisation problem. Existing PFSP variants capture different realistic scenarios, but significant modelling gaps still remain with respect to many ...

• We consider and review different representations, sequencing rules, and assignment rules.

In this paper we address the classical hybrid flow shop scheduling problem with makespan objective. As this problem is known to be NP-hard and a very common layout in real-life manufacturing scenarios, many studies have been proposed ...

• We study a capacitated inventory system under static-dynamic uncertainty strategy.

We consider a lot-sizing problem in a single-item single-stage production system facing non-stationary stochastic demand in a finite planning horizon. Motivated by common practice, the set-up times need to be determined and frozen once ...

• A single-product, single-location decaying inventory system is considered.
• ...

In this paper, a single-product, single-location inventory system is considered. A fraction of the stock is lost every time unit, i.e., inventory experiences continuous decay. Demand is uncertain and replenishments require a positive ...

• Crowdshipping is a new solution to lower costs for transportation companies.
• ...

Technological advances in the past decades have sparked numerous creative and innovative solutions to lower costs for transportation companies. One such solution, adopted by Walmart and Amazon among others, is crowdshipping, i.e. ...

• Pattern-based models for a two-dimensional two-stage guillotine cutting stock problem are analyzed and compared.

This study presents a theoretical and computational analysis of integer programs based on the concept of the patterns, the so-called pattern-based models, for a two-dimensional two-stage guillotine cutting stock problem. The full-...

• A mixed integer non-linear bi-level model is developed for simultaneous decisions in road traffic management

In the context of vehicle transportation in congested roads, we propose an optimization framework to integrate the operator decisions on network pricing, regulation, and expansion, while accounting for the shipments of hazardous ...

• The single-machine completion time variance problem 1||CTV is studied from the viewpoint of exact solutions.

This paper studies a single machine scheduling problem to minimize the completion time variance (CTV) of all jobs. A new time-indexed quadratic programming formulation is proposed, in which the quadratic terms are further linearized ...

• An inventory problem where the inventory cycle must be an integer multiple of a basic time period is studied.

A deterministic inventory model for goods with a power demand pattern, allowing backlogged shortages, is analyzed. The inventory cycle must be an integer multiple of a fixed time period (called basic period). Demand follows a power ...

Recent advances on the polyhedral combinatorics of the Balanced Minimum Evolution Problem (BMEP) enabled the identification of fundamental characteristics of the convex hull of the BMEP (or BMEP polytope) as well as the description of ...

• This paper concentrates on a capacitated multi-period cutting stock problem with pattern setup cost.

This paper concentrates on a capacitated multi-period cutting stock problem. In the production process, multiple identical input rods can be bundled together and cut simultaneously. We say that these input rods are cut with the same ...

• A meta-heuristic solution approach using extended networks is presented.
• Four ...

This paper presents a new solution algorithm to solve the resource-constrained project scheduling problem with activity splitting and setup times. The option of splitting activities, known as activity preemption, has been studied in ...

• The main objective of the paper is to solve the optimization problem associated with the classification of DNA samples in PCR plates for Sanger sequencing.

The main objective of this paper is to solve the optimization problem that is associated with the classification of DNA samples in PCR plates for Sanger sequencing. To achieve this goal, we design an integer linear programming model. ...

• Two new theoretical lower bounds for Minimum Sum Coloring and Optimum Cost Chromatic Partition are proposed.

The Minimum Sum Coloring Problem (MSCP) and Optimum Cost Chromatic Partition Problem (OCCP), variants of the well-known Graph Coloring Problem (GCP), find applications in different domains, such as VLSI design, resource allocation, ...

• A new parallelised differential evolution algorithm to locate multiple local optima for resource constrained job scheduling problems is proposed.

Resource constrained job scheduling problems are ubiquitous in real-world logistics and supply chain management. By solving these optimisation problems, organisations can efficiently utilise logistical resources and improve delivery ...

• We seek to determine the best locations for EV charging stations under driving range uncertainty.

We seek to determine the best locations for electric vehicle fast charging stations under driving range uncertainty. Two stochastic programming based models have been recently proposed to handle the resulting stochastic flow refueling ...

• Novel portfolio design including cardinality constraint and risk parity condition in the set of constraints.

The financial crisis and the market uncertainty of the last years have pointed out the shortcomings of traditional portfolio theory to adequately manage the different sources of risk of the investment process. This paper addresses the ...

• We propose MDRP, a new routing problem for a set or swarm of drones.
• A ...

In this paper, we address the problem of finding trajectories for multiple unmanned aerial vehicles deployed to perform a collaborative mission, requiring communication, coordination and situation awareness. Thus, we favor trajectories ...

• We study vehicle routing problem with drones and en route operations,
• formulate ...

With the goal of integrating drones in last-mile delivery, the Vehicle Routing Problem with Drones (VRPD) uses a fleet of vehicles, each of them equipped with a set of drones, for serving a set of customers with minimal makespan. In ...