Reactive Scheduling Systems

In most practical environments, scheduling is an ongoing reactive process where evolving and changing circumstances continually force reconsideration and revision of pre-established plans. Scheduling research has traditionally ignored this "process view" of the problem, focusing instead on optimization of performance under idealized assumptions of environmental stability and solution executability. In this paper, we present work aimed at the development of reactive scheduling systems, which approach scheduling as a problem of maintaining a prescriptive solution over time, and emphasize objectives (e.g., solution continuity, system responsiveness) which relate directly to effective development and use of schedules in dynamic environments. We describe OPIS, a scheduling system designed to incrementally revise schedules in response to changes to solution constraints. OPIS implements a constraint-directed approach to reactive scheduling. Constraint analysis is used to prioritize outstandin..

Sistemas de coordenação de ordens: revisão, classificação, funcionamento e aplicabilidade Systems for coordinating orders: review, classification, operationality and applicability

O foco deste trabalho são os ordering systems, os quais são sistemas de informação que programam ou organizam as necessidades em termos de componentes e materiais e/ou controlam a emissão/liberação das ordens de produção e compra, podendo conter ou não regras de seqüenciamento das ordens. Dentro deste contexto, o presente artigo tem por objetivos: apresentar uma nova nomenclatura para os ordering systems, sistemas de coordenação de ordens de produção e compra (SCO); apresentar uma tipologia que permita classificar os diversos sistemas de forma racional; destacar alguns sistemas altamente promissores em termos de aplicação e que são relativamente desconhecidos no Brasil e, trazer à tona um tema importantíssimo dentro do planejamento e controle da produção (PCP) e que está um tanto esquecido na literatura científica nacional.<br>Ordering systems are the focus of this work. Ordering systems are information systems which schedule or organize requirements in terms of components and materials and/or control the production and purchase orders emission/release being able to restrain or not rules of sequencing orders. Within this context, this paper intends: to present a new nomenclature for ordering systems, Systems for Coordinating purchase and production Orders (SCO); to present a typology that is able to classify all the systems in a rational way; to discuss some systems which have high potential for success applications and that are relatively unknown in Brazil and, to highlight a theme which is highly important to Production Planning and Control (PPC) in the scientific Brazilian literature