[pt] Apesar de existir na literatura modelos propostos para gestão de estoques, as premissas consideradas por tais modelos podem inviabilizar suas aplicações. Este trabalho propõe uma metodologia de programação estocástica para reposição e controle de estoques de produto único numa rede logística de duas camadas. O enfoque revisão periódica proposto pode considerar tanto atendimentos à demanda em atraso (backorders) como vendas perdidas (lost sales) sem restrição de pedidos pendentes. Além disso, a fim de alcançar um melhor nível de serviço para o cliente, é introduzida uma regra de rateio proporcional a quantidade faltante do item em estoque no centro de distribuição para atender simultaneamente a demanda de todos os varejistas, a qual é capaz de lidar com as alocações negativas da falta. A periodicidade e o nível alvo da posição dos estoques são determinados através de modelos de programação estocástica de dois estágios e de uma técnica baseada em simulação de Monte Carlo, conhecida como Sample Average Approximation, que levam em conta a natureza incerta dos níveis de demanda pelo item por meio da geração de conjuntos finitos de cenários. Os equivalentes determinísticos são apresentados como modelos de programação não-linear inteira mista e em seguida linearizados. Experimentos numéricos com a metodologia proposta para instâncias do problema geradas aleatoriamente demonstram seu potencial ao obter resultados com erros de aproximadamente 1 por cento. / [en] Although several methods for inventory management are proposed in the literature, the required assumptions can hinder their application in practice. This work proposes a methodology for stock replenishment in two-echelon logistic networks through stochastic programming, considering a single item, periodic review and uncertain demands. The proposed approach is flexible enough to consider backlogs and lost sales cases without limitations on the number of outstanding orders. Also, in order to achieve better customer service, we introduce a variable rationing rule for quantities of the item in short at the distribution center to meet simultaneously all the demands of the retailers, dealing with imbalances or negative allocations of quantities of the item in short. The optimal review periodicity and the target level for inventory position are determined through two-stage stochastic programming models and a Monte Carlo simulation based-technique, known as Sample Average Approximation, which takes into account the uncertain nature of the item demand levels through the generation of finite sets of scenarios. The deterministic equivalent models are presented as mixed-integer non-linear programming models, which are then linearized. Numerical experiments with the proposed approach for instances of the problem randomly generated shows its potential, as the errors of the obtained results are around 1 percent.

Kompetenzzellenbasierte (regionale) Netze stellen besondere Anforderungen an die Modellierung, Planung und Gestaltung der Logistikstrukturen. Für die Logistikstrukturmodellierung werden ein generischer Beschreibungsrahmen für produktionslogistische soziotechnische Systeme, Definitionen u.a. zum zentralen Begriff Logistikstruktur sowie ein 3-Ebenen-Modell und Strukturtypen für eine vertiefende Materialflussanalyse und -synthese bereitgestellt. Für die Logistikstrukturplanung wird darauf aufbauend mit der Methode der Integrativen Prozess- und Systemstrukturierung (IPSS) eine Methode zur Behandlung von Strukturierungsproblemen konzipiert, die sowohl speziell für kompetenzzellenbasierte Netze als auch allgemein für Produktions- und Logistiksysteme angewandt werden kann. Für die Logistikstrukturgestaltung werden unter Modell- und Methodenverwendung Szenarien sowie Gestaltungs- und Vorzugslösungen für den Materialfluss abgeleitet. / Competence-cell based (regional) networks put special requirements on the modelling, planning and design of logistics structures. For the modelling of logistics structures, a generic description framework for production logistic sociotechnical systems, definitions for, amongst others, the central term logistics structure as well as a 3-layer-model and structure types for a more detailed material flow analysis and synthesis are provided. For the planning of logistics structures, the Method of Integrative Process and System Structuring (IPSS) is developed as a method for handling structuring problems. It can be applied especially to Competence-cell based networks as well as generally to production and logistics systems. For the design of logistics structures, scenarios as well as design and preference solutions for the material flow are derived.

Kompetenzzellenbasierte (regionale) Netze stellen besondere Anforderungen an die Modellierung, Planung und Gestaltung der Logistikstrukturen. Für die Logistikstrukturmodellierung werden ein generischer Beschreibungsrahmen für produktionslogistische soziotechnische Systeme, Definitionen u.a. zum zentralen Begriff Logistikstruktur sowie ein 3-Ebenen-Modell und Strukturtypen für eine vertiefende Materialflussanalyse und -synthese bereitgestellt. Für die Logistikstrukturplanung wird darauf aufbauend mit der Methode der Integrativen Prozess- und Systemstrukturierung (IPSS) eine Methode zur Behandlung von Strukturierungsproblemen konzipiert, die sowohl speziell für kompetenzzellenbasierte Netze als auch allgemein für Produktions- und Logistiksysteme angewandt werden kann. Für die Logistikstrukturgestaltung werden unter Modell- und Methodenverwendung Szenarien sowie Gestaltungs- und Vorzugslösungen für den Materialfluss abgeleitet. / Competence-cell based (regional) networks put special requirements on the modelling, planning and design of logistics structures. For the modelling of logistics structures, a generic description framework for production logistic sociotechnical systems, definitions for, amongst others, the central term logistics structure as well as a 3-layer-model and structure types for a more detailed material flow analysis and synthesis are provided. For the planning of logistics structures, the Method of Integrative Process and System Structuring (IPSS) is developed as a method for handling structuring problems. It can be applied especially to Competence-cell based networks as well as generally to production and logistics systems. For the design of logistics structures, scenarios as well as design and preference solutions for the material flow are derived.