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Detalhes

Detalhes

004
Publicações

2019

Capacitated Vehicle Routing Problem with Heterogeneous Fixed Proprietary Fleet and Outsourcing Delivery—A Clustering-Based Approach

Autores
Bertoluci, R; Ramos, AG; Lopes, M; Bastos, J;

Publicação
Springer Proceedings in Mathematics and Statistics

Abstract
This paper describes a solution method that was created with the objective of obtaining a more efficient finished goods distribution process for a food industry company. The finished goods distribution process involves the use of the companys own fleet to serve a specific group of customers, and the use of outsourcing transportation services that can make direct and transshipment customer deliveries. The complexity of the problem is due to the need to decide which customers should be served by each of the outsourcing transportation services, direct or transshipment, and to find cost efficient solutions for the multiple vehicle routing problems created. First, an original clustering method consisting of a logical division of the customer orders using a delivery ratio based on the transportation unit cost, distance and order weight, is used to define customer clusters by service type. Then, an exact method based on a mixed integer programming model, is used to obtain optimal vehicle routing solutions, for each cluster created. The solution method for the company real instances, proved able to reach the initial proposed objectives and obtain promising results that suggest an average reduction of 34% for the operational costs, when compared to the current distribution model of the company. © 2019, Springer Nature Switzerland AG.

2018

A new Load Balance Methodology for Container Loading Problem in Road Transportation

Autores
Ramos, AG; Silva, E; Oliveira, JF;

Publicação
European Journal of Operational Research

Abstract

2018

Cargo stability in the container loading problem - State-of-the-art and future research directions

Autores
Ramos, AG; Oliveira, JF;

Publicação
Springer Proceedings in Mathematics and Statistics

Abstract
The purpose of this paper is to present the current understanding and conceptualization of the cargo stability constraint within the context of the Container Loading Problem. This problem is highly relevant in the transportation industry due to the increasing pressure for a more economically, environmentally and socially efficient and sustainable cargo transportation. Stability is one the most important practical relevant constraints in the Container Loading Problem due to its strong influence on the cargo arrangement. Stability is usually divided into stability during loading operations (static) and stability during transportation (dynamic). Two main contributions are made. Firstly, an overview of recent developments in the literature on the two types of stability, static and dynamic, is provided. Secondly, of opportunities for future research are identified. © Springer International Publishing AG 2018.

2018

An intercontinental replenishment problem: A hybrid approach

Autores
Silva, E; Ramos, AG; Lopes, M; Magalhaes, P; Oliveira, JF;

Publicação
Springer Proceedings in Mathematics and Statistics

Abstract
This work addresses a case study in an intercontinental supply chain. The problem emerges in a company in Angola dedicated to the trade of consumable goods for construction building and industrial maintenance. The company in Angola sends the replenishment needs to a Portuguese company, which takes the decision of which products and in which quantities will be sent by shipping container to the company in Angola. The replenishment needs include the list of products that reached the corresponding reorder point. The decision of which products and in which quantity should take into consideration a set of practical constraints: the maximum weight of the cargo, the maximum volume the cargo and financial constraints related with the minimum value that guarantees the profitability of the business and a maximum value associated with shipping insurance. A 2-stage hybrid method is proposed. In the first stage, an integer linear programming model is used to select the products that maximise the sales potential. In the second stage, a Container Loading Algorithm is used to effectively pack the selected products in the shipping container ensuring the geometrical constraints, and safety constraints such as weight limit and stability. A new set of problem instances was generated with the 2DCPackGen problem generator, using as inputs the data collected in the company. Computational results for the algorithm are presented and discussed. Good results were obtained with the solution approach proposed, with an average occupation ratio of 92% of the container and an average gap of 4% for the solution of the integer linear programming model. © Springer International Publishing AG 2018.

2018

Load balance recovery for multi-drop distribution problems: A mixed integer linear programming approach

Autores
Silva, E; Ramos, AG; Oliveira, JF;

Publicação
Transportation Research Part B: Methodological

Abstract
In road freight transport, a loaded vehicle with a distribution route and a compliant load balance at the depot can become non-compliant during the route, since the total weight of the cargo and its centre of gravity change with each delivery. Nowadays, vehicles circulating on our roads either undermine safety regulations or lack operational efficiency when these regulations are taken into account and cargo is extensively rearranged after each delivery. This issue has been completely ignored both in the vehicle routing literature and in the container loading literature. The aim of this work is to provide tools capable of ensuring that a cargo arrangement is load balanced along the complete distribution trip. It proposes a multi-drop load balance recovery algorithm (MDLBRA), which seeks to ensure that, when both a complete route and the respective cargo arrangement are provided, the boxes to be removed from the cargo arrangement at the depot and the boxes to be rearranged at each customer are identified, allowing the cargo to remain balanced after every delivery. It is important to notice that a MDLBRA is not a container loading algorithm: a MDLBRA modifies solutions generated by any container loading algorithm so that load balance is guaranteed when the truck leaves the depot and during the entire distribution route. A mixed integer linear programming (MILP) model is proposed to balance the cargo at each customer stop. The MILP model incorporates load distribution diagram constraints in order to determine the feasible domain for the location of the centre of gravity of the cargo arrangement, taking into account the regulatory requirements and the technical characteristics of the vehicle. Extensive computational experiments show that a MDLBRA can be used in practical contexts, as the MILP model was able to find a solution in less than ten minutes in 93% of the unbalanced test instances. © 2018 Elsevier Ltd

Teses
supervisionadas

2019

O problema de carregamento de contentores - Uma nova abordagem baseada em programação inteira

Autor
CLÁUDIA RAQUEL OLIVEIRA GONÇALVES

Instituição
IPP-ISEP

2019

Desenvolvimento de um modelo de manutenção da rede de transportadores de garrafas de vidro

Autor
JOÃO NUNO ROCHA DE SOUSA MACHADO GONÇALVES

Instituição
IPP-ISEP

2018

Melhoria dos processos de ensaios e calibrações no laboratório de metrologia e ensaios do IEP

Autor
FERNANDO DOS SANTOS MOREIRA

Instituição
IPP-ISEP

2018

Localização da physical interntet hub na Península Ibérica

Autor
TIAGO MANUEL FERNANDES DE FREITAS PEIXOTO

Instituição
IPP-ISEP

2018

MÉTODOS DE ANÁLISE DA COMPLEXIDADE NO PROBLEMA DE EMPACOTAMENTO DE PALETES DO DISTRIBUIDOR

Autor
HUGO ANDRÉ DE ALMEIDA BARROS

Instituição
IPP-ISEP