A relax-and-fix with fix-and-optimize heuristic applied to multi-level lot-sizing problems

In this paper, we propose a simple but efficient heuristic that combines construction and improvement heuristic ideas to solve multi-level lot-sizing problems. A relax-and-fix heuristic is firstly used to build an initial solution, and this is further improved by applying a fix-and-optimize heuristic. We also introduce a novel way to define the mixed-integer subproblems solved by both heuristics. The efficiency of the approach is evaluated solving two different classes of multi-level lot-sizing problems: the multi-level capacitated lot-sizing problem with backlogging and the two-stage glass container production scheduling problem (TGCPSP). We present extensive computational results including four test sets of the Multi-item Lot-Sizing with Backlogging library, and real-world test problems defined for the TGCPSP, where we benchmark against state-of-the-art methods from the recent literature. The computational results show that our combined heuristic approach is very efficient and competitive, outperforming benchmark methods for most of the test problems

Service-Oriented Architecture to Integrate Flight Safety and Mission Management Subsystems into UAVs

This paper presents the design and implementation of a Service-Oriented Architecture (SOA) to tackle with the data exchange different elements onboard the Unmanned Aerial Vehicle (UAV) and the real-time safety critical operation of In-Flight Awareness Augmentation System (IFA2S) and non-safety critical Mission Oriented System Array (MOSA), respectively to take care of flight safety and mission accomplishment

Evaluating genetic algorithms with different population structures on a lot sizing and scheduling problem

This paper studies the use of different population structures in a Genetic Algorithm (GA) applied to lot sizing and scheduling problems. The population approaches are divided into two types: single-population and multi-population. The first type has a non-structured single population. The multi-population type presents non-structured and structured populations organized in binary and ternary trees. Each population approach is tested on lot sizing and scheduling problems found in soft drink companies. These problems have two interdependent levels with decisions concerning raw material storage and soft drink bottling. The challenge is to simultaneously determine the lot sizing and scheduling of raw materials in tanks and products in lines. Computational results are reported allowing determining the better population structure for the set of problem instances evaluated. Copyright 2008 ACM

Abrir a caixa-preta e refletir sobre métodos do fazer. Otimização de projeto orientado ao desempenho em arquitetura

Fil: da Silva Digiandomenico, Dyego. Universidade Católica de Pernambuco. Brasil.Fil: Landim, Gabriele do Rosario. Pontifícia Universidade Católica de Minas Gerais. Brasil.Fil: Motta Toledo, Claudio Fabiano. Universidade de São Paulo. Instituto de Ciências Matemáticas e de Computação. Brasil.Algoritmos de otimização integrados ao projeto computacional têm despertado cada vez mais interesse em arquitetura e urbanismo. Chamamos atenção para uma prática frequente na área de projeto computacional: publicar pesquisas em otimização sem explicitar, detalhar os compartilhar os conjuntos de procedimentos que levaram aos resultados otimizados. A falta de compartilhamento dos métodos e procedimentos aplicados à otimização de projetos de arquitetura pode produzir conclusões inseguras, desamparar discussões sobre as soluções e inviabilizar sua replicabilidade, além de dificultar a análise crítica do processo. Discutimos detalhes emergidos ao transitar entre a aplicabilidade técnica de um algoritmo de otimização aberto e o que aprendemos deste processo de maneira mais ampla e crítica para a produção no sul global

Meta-heuristic approaches for a soft drink industry problem

The present paper evaluates meta-heuristic approaches to solve a soft drink industry problem. This problem is motivated by a real situation found in soft drink companies, where the lot sizing and scheduling of raw materials in tanks and products in lines must be simultaneously determined. Tabu search, threshold accepting and genetic algorithms are used as procedures to solve the problem at hand. The methods are evaluated with a set of instance already available for this problem. This paper also proposes a new set of complex instances. The computational results comparing these approaches are reported. © 2008 IEEE