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19th EMSS, 2007 |
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19th European Modeling and Simulation Symposium (Simulation in Industry) 4-6 October 2007 Bergeggi (Sv), Italy |
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Session CO-VI: Petri Nets II
REDESIGN OF A PICKING PROCESS USING A SIMULATION MODEL, Miquel Angel Piera, Roman Buil
The use of stationary based methods for warehouse designs usually leads to two different alternatives: over sizing infrastructure to absorb picks in the demand which increases the overall cost, or designs that fall short to deal with the dayto- day demand due to a shortage on resource sizing. An in-depth look at how a simulation model can be used to aid in the design of a new warehouse is presented, specifying the labor and equipment required to support warehouse operations.
A CPN MODEL FOR CREW MANAGEMENT, M. Piera, N. Munoz, M. Narciso
Traditional network carriers have a wide range of customer segments, wide market/segment coverages with high costs and large and costly hubs, whereas Low Cost Companies (LCCs) have a narrower customer segment focus, low complexity/lean production model, standard fleet, no partnerships with hub operators and optimisation around asset/fleet utilisation productivity. LCC are constantly looking for new models that could provide significant across-the-board cost advantages. In this paper we will introduce a discrete event system specification of the flight time limitation scheme (FTLS), that will allow to determine the minimum crew required to support a certain flight planning. A particular FTLS is defined under the Coloured Petri Net (CPN) formalism that can be used to deal with an optimal crew roster for a certain month flight planned schedules by analyzing the state space of the model.
PETRI NET MODELLING AND DEADLOCK ANALYSIS OF PROGRAMMABLE LOGIC CONTROL, Gasper Music, Borut Zupancic
The paper presents a methodology of deriving closed loop model of a discretely controlled process. The aim is to enable the analysis of control logic that is implemented by industrial programmable logic controllers. A two stage approach is adopted. In the first stage a set of interlock supervisors is designed based on Petri net model of the plant and a set of interlock specifications. In the second stage the model of admissible behaviour is used as a plant model to form a closed-loop with a sequential controller. This enables the verification of the sequential specification model in a form of a Petri net. The basic property of interest is the absence of dead-lock in the closed loop.
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