Abstract
This paper presents some concepts related with the development of a "model generator" for simulating supply chain systems. Such concepts arise not only from the object point of view taken over this system, but also from our intention to synthesise the behaviour of such kind of systems in a more general form, in particular concerning the events and activities related with suppliers, factories, warehouses, retailers, and even the last customers, which in fact trigger the flow of materials and information on the chain. Unlike the static approaches usually used for strategic purposes, where parameters like the time of delivery or the average rate of material flow are held as inputs to the system, the ideas described here consider a dynamic representation of the supply chain in which those parameters are results of some detailed simulation process. what gives this approach the ability of modelling those systems starting from the less abstract point of view to a more abstract representation. The result is a more realistic picture of the dynamics involved. Due to this fact, this approach could be seen as being more directed to managers than to strategists. Nevertheless, the objective is also that the models can be used to simulate either short or long periods of time, revealing their usefulness also for strategic analysis. The basis of these ideas is to consider the flow of products, information and money between any elements in the chain as a general form of customer-supplier exchange activity, and also by treating each of those elements as inheriting from a single element which includes the basic behaviour (and resources) of a factory, warehouse and retailer. A description of such element will be made. explaining its structure and the associated fixed and variable costs of its various processes. As we will see, many parameters considered inputs to other modelling techniques will appear here as outputs. giving the analyst more interesting data with which it can measure the supply chain performance by means of any statistical methods.

Abstract
This paper describes a new heuristic for the nesting problem based on a 2-exchange neighbourhood generation strategy. This mechanism guides the search through the solution space consisting of the sequences of pieces and relies on a low-level placement heuristic to actually convert one sequence in a feasible layout. The placement heuristic is based on a bottom-left greedy procedure with the ability to fill holes in the middle of the layout at a later stage. Several variants of the 2-exchange nesting heuristic were implemented and tested with different initial solution ranking criteria, different strategies for selecting the next solution, and different neighbourhood sizes. The computational experiments were based on data sets published in the literature. In most of the cases, the 2-exchange nesting algorithm generated better solutions than the best known solutions.

Abstract

Abstract
In recent years, the ISO 9000 standard has experienced an extraordinary success. The number of certifications is still increasing worldwide and it is expected that this trend will last. In fact, ISO 9000 certification has become an important factor for doing business in the global market. However, there are many contradictory opinions regarding the real benefits of ISO registration. This paper contributes to this debate by empirically investigating the impact on the Portuguese stock market of achieving ISO 9000 certification. The analysis is based on the event study methodology. The findings suggest that the market positively anticipates the event. A favourable effect is also detected in achieving an early registration within the relevant sector or industry. A financial performance analysis covering a 5-year period centred on the year of the ISO 9000 certification was also carried out. The results suggest that the ISO 9000 certification have a powerful cost effect, decreasing the operating performance and the profitability in the year following the certification. Apparently, companies need one more year to recover those costs.

Abstract
This paper describes an application of genetic algorithms to the bus driver scheduling problem. The application of genetic algorithms extends the traditional approach of Set Covering/Set Partitioning formulations, allowing the simultaneous consideration of several complex criteria. The genetic algorithm is integrated in a DSS but can be used as a very interactive tool or a stand-alone application. It incorporates the user's knowledge in a quite natural way and produces solutions that are almost directly implemented by the transport companies in their operational planning processes. Computational results with airline and bus crew scheduling problems from real world companies are presented and discussed.

Abstract
This paper introduces a new upper bound to the problem of fitting identical circles into a rectangle. This problem is usually referred to as the ‘cylinder packing problem’ or ‘cylinder palletization’. In practice, it arises when it is desired to maximize the number of cylindrical items packed in an upright position onto a rectangle/pallet. The upper bound developed consists in determining the reduced pallet area by deducting a lower bound for the unused pallet area from the total area of the pallet. The upper bound for the number of identical circles to pack into the pallet is computed by the ratio reduced pallet area/circle area. The results obtained for five distinct sets of problems are analyzed and compared with previous bounds found in the published literature. International Federation of Operational Research Societies 2001.