Abstract
In this article we present a practical example where the concept of Holistic Metrics (Feliz-Teixeira & Brito, 2006) is used as a way for sensing the results obtained in a simulation study related to the Portuguese enterprise GalpEnergia. Previously described in Feliz-Teixeira & Brito (2005), that case is used again in this article in order to demonstrate the practical value of the Holistic Metrics concept. This is basically a simple method for estimating or characterizing the behaviour of complex systems, in particular when these are studied throughout simulation. Instead of treating the complex output data obtained from this kind of system along the time domain, this perspective encourages analysts to represent such data in the frequency domain, somewhat as is adopted in Fourier Analysis and in Quantum Mechanics.

Abstract
This work aims to determine the effect of performing age based preventive maintenance actions on a repairable system with a constant failure rate. Periodic overhauls are carried out every time the system reaches the end of a constant time interval without failures and the system is repaired whenever a failure occurs. Performing overhauls implies interventions such as: replacement of parts with increasing hazard rate, cleaning, oiling etc. In this work, the relationship between the initial failure rate (without periodic overhauls) and the failure rate with periodic overhauls is established. © 2008 ICQR.

Abstract
In production planning in the glass container industry, machine-dependent setup times and costs are incurred for switch overs from one product to another. The resulting multi-item capacitated lot-sizing problem has sequence-dependent setup times and costs. We present two novel linear mixed-integer programming formulations for this problem, incorporating all the necessary features of setup carryovers. The compact formulation has polynomially many constraints, whereas the stronger formulation uses an exponential number of constraints that can be separated in polynomial time. We also present a five-step heuristic that is effective both in finding a feasible solution (even for tightly capacitated instances) and in producing good solutions to these problems. We report computational experiments.

Abstract

Abstract
This paper presents a very special cutting path determination problem appearing in a high precision tools factory, and provides two new heuristics for its resolution. Particular features of both the cutting process, and of the material to be cut, bring in a set of unusual constraints, when compared with other cutting processes, which confer additional complexity and originality to the problem. In particular, this is a matter of practical and economic relevance, since the solution methods are intended to be implemented in a real-life industrial environment. The concept of dynamic graph is exploited to deal with the arc routing problem under study, which is modelled as a dynamic rural postman problem. The constructive heuristics developed, the "higher up vertex heuristic" (HUV) and the "minimum empty path heuristic" (MEP) are tested with real data sets.

Abstract
In this paper we present an extension of the Nelder and Mead simplex algorithm for non-linear programming, which makes it suitable for both unconstrained and constrained optimisation.(1) We then explore several extensions of the method for escaping local optima, which make it a simple, yet powerful tool for optimisation of nonlinear functions with many local optima. A strategy which proved to be extremely robust was random start local search, with a correct, though unusual, setup. Actually, for some of the benchmarks, this simple metaheuristic remained the most effective one. The idea is to use a very large simplex at the begin; the initial movements of this simplex are very large, and therefore act as a kind of filter, which naturally drives the search into good areas. We propose two more mechanisms for escaping local optima, which, still being very simple to implement, provide better results for some difficult problems.