The paper summarizes the results of research on the modeling and implementation of advanced planning and scheduling (APS) systems done in recent twenty years. It discusses the concept of APS system-how it is thought of today-and highlights the modeling and implementation challenges with which the developers of such systems should cope. Some from these challenges were identified as a result of the study of scientific literature, others-through an in-depth analysis of the experience gained during the development of real-world APS system-a Production Efficiency Navigator (PEN system). The paper contributes to APS systems theory by proposing the concept of an ensemble of collaborating algorithms.
The paper proposes a novel predictive-reactive planning and scheduling framework in which both approaches are combined to complement each other in a reasonably balanced way. Neither original scheduling algorithms nor original techniques can be find in this paper. It also does not intend to invent new mechanisms or to propose some cardinally new ideas. The aim is to choose, adapt and test ideas, mechanisms and algorithms already proposed by other researchers. The focus of this research is set on make-to-order production environments. The proposed approach aims not only to absorb disruptions in shop floor level schedules but also to mitigate the impacts of potential exceptions, which disrupt mid-term level production plans. It is based on application of risk mitigation techniques and combines various simulation techniques extended by optimization procedures. The proposed approach is indented to be implemented in Advanced Planning and Scheduling system, which is an add-on for Enterprise Resources Planning system. To make it easier to understand the focus of the paper, at the beginning the position from which we start is clarified.
The paper analyses the problem of aggregation of internal quality characteristics of an information system specification language. It surveys main categories of aggregation operators, their mathematical and behavioural properties and proposes how to aggregate quality characteristics taking into account measurements of all lowest-level characteristics in a proper way. The paper shows that four different kinds of dependencies can occur among characteristics of internal quality and discusses in detail what aggregation techniques are reasonable for each case. It also describes a heuristic for minimisation of possible deviations of measurement results obtained after using a number of different metrics or because of the inaccuracy of used measurement techniques.
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