Simulation Integrated Design for Logistics

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Transcript of Simulation Integrated Design for Logistics

Hans P.M. Veeke March, 2003

Simulation Integrated Design for Logistics

Proefschriftter verkrijging van de graad van doctor aan de Technische Universiteit Delft op gezag van de Rector Magnificus prof. dr. ir. J.T. Fokkema, voorzitter van het College voor Promoties, in het openbaar te verdedigen op dinsdag 24 juni 2003 om 10.30 uur door Hermanus Petrus Maria VEEKE wiskundig ingenieur geboren te Breda

Dit proefschrift is goedgekeurd door de promotoren: Prof. dr. ir. G. Lodewijks Prof. ir. H. Bikker

Samenstelling promotiecommissie: Rector Magnificus Prof. dr. ir. G. Lodewijks Prof. ir. H. Bikker Prof. dr. ir. J.A.E.E. van Nunen Prof. dr.-ing. H.J. Roos Prof. dr. ir. R. van Landeghem Prof. ir. J. in t Veld Dr. ir. J.A. Ottjes voorzitter Technische Universiteit Delft, promotor Technische Universiteit Delft, promotor Erasmus Universiteit Rotterdam Universitt Stuttgart Universiteit Gent Technische Universiteit Delft Technische Universiteit Delft

Published and distributed by: DUP ScienceDUP Science is an imprint of Delft University Press P.O.Box 98 2600 MG Delft The Netherlands Telephone: +31 15 27 85 678 Telefax: + 31 15 27 85 706 E-mail: [email protected] ISBN 90-407-2417-2 Keywords: systems approach, logistics, process interaction simulation Copyright 2003 by H.P.M. Veeke All rights reserved. No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without written permission from the publisher: Delft University Press Printed in the Netherlands

AcknowledgementsImagine you have an independent profession with a sixty-hour working week and a family with four adolescent kids, then the conditions for writing a thesis are certainly not optimal. The success heavily depends on the support of the environment. Therefore, I do not consider this thesis as a result of me alone, but as the result of the many people who have supported me. First of all I thank Mies, Bart, Jeroen, Max and Maartje for accepting the fact that the back of my head became more familiar to them than my face, which was staring to the screen mostly. I will certainly turn around more often from now on. At the professional side many people have helped me in writing this thesis. Firstly I wish to thank Gabriel Lodewijks, because he made the conditions to let me work on this thesis without any real worries. I have experienced the discussions with him and my other supervisor, Henk Bikker, as very productive and creative. I hope to continue the cooperation with both of them in future. Secondly my thanks go to my colleagues of the departments Production Technology and Organization, and Marine and Transport Technology. Some helped me by reviewing intermediate results, others by offering literature and challenging brainstorms. Finally, there are three people that I wish to thank explicitly. I would like to express my gratitude to Jan in t Veld. I am not exaggerating when I say that he has learned me to think and whats more, to be practical. I will never forget the moment when I presented my first results of academic research under his supervision. Within two minutes I was outside again, because my conditions were unacceptable in practice though scientifically correct. From that moment on, I realized that academic research and practical applicability are two different things and I took a lot of advantage of this experience. Secondly, I am very grateful to Joan Rijsenbrij. I met him during the challenging Delta SeaLand project in the late eighties. It was a unique experience and I learned a lot of him in stimulating people to achieve a goal that seems impossible to be reached at some times. It was the first time of my life I was locked up in a room with a few others and we were only allowed to leave it when we found a working solution. We did find it! And finally I thank Jaap Ottjes, who I consider more than a colleague. I extremely enjoy our cooperation in the field of simulation. To be able to correctly implement the things we invent, you always need someone who is able to define the correct things.

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SummaryThe design of an innovative logistic system is a complex problem in which many different disciplines are involved. Each discipline developed its own way of conceptual modeling for a logistic system based on a mono disciplinary perception. It usually leads to a communication problem between the different disciplines and consequently to expectations of the performance that dont correspond with reality. In this thesis a basic systems approach is used to define a conceptual model of a logistic system that can be used by all disciplines involved as a common reference of the design. A combination of a soft and a hard systems approach leads to a conceptual model in which the problem is formulated in terms of required performances and process structures. The logistic system is modeled as a structure of functions around three flows: orders, products and resources. The model evolves during the design project and is an enduring supporting tool for decision making with a clear relation to the systems objectives. This PROcessPERformance model (PROPER) model is formulated in interdisciplinary terms and thereby enables the communication between different disciplines. The PROPER model only reflects the structure of a system; it does not model the time dependent behavior of the system. This behavior is essential for correct decision making and usually this behavior is simulated on a computer. In practice simulation is only used during the final stages of a design project and then a correction of objectives and/or decisions is impossible or very expensive. In this thesis the use of simulation is recommended for decision making from the very start. To achieve this the description of time dependent behavior is also defined at an interdisciplinary level. Natural language is used to describe the processes as defined in the PROPER model at each aggregation stratum. These descriptions enrich the problem formulation phase by expressing the parallel and stochastic aspects of the system. Like the other disciplines, simulation evolved as a specialist discipline. In order to preserve a direct connection with the process descriptions of the PROPER model, these natural language process descriptions are translated into an object oriented Process Description Language PDL. This language can be implemented in any object oriented software environment. It is here implemented in the Borland Delphi platform that is based on the programming language Pascal. The implementation is called TOMAS: Tool for Object

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oriented Modeling And Simulation. TOMAS is completely object oriented and fully complies with the Process Interaction implementation of the Discrete Event System Specification method (DEVS). In order to support the growing level of detail of the PROPER model during a design project, TOMAS also supports distributed simulation by offering an open event scheduling mechanism and communication between models at different aggregation strata. Finally the use of PROPER, PDL and TOMAS is illustrated with an already finished complex project: the design of the first automated container terminal in Rotterdam. It is shown that the use of this approach would have led to a clear and complete objective definition and would have warned the project participants in an early stage for a mismatch between expected and real operational performance. This approach will therefore not automatically lead to improved logistic designs, but it does contribute to a better correspondence between expectations and reality.

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SamenvattingHet ontwerpen van een innovatief logistiek systeem is een complex probleem, waarin vele verschillende disciplines zijn betrokken. Elke discipline ontwikkelde op eigen wijze conceptuele modellen van een logistiek systeem, die gebaseerd zijn op een monodisciplinaire perceptie. In het algemeen is dit de aanleiding voor een communicatieprobleem tussen de verschillende disciplines met als gevolg dat de verwachtingen ten aanzien van de prestaties niet overeenkomen met de werkelijkheid. In dit proefschrift wordt een fundamentele systeembenadering gebruikt om een conceptueel model voor een logistiek systeem te ontwikkelen; dit model kan door alle disciplines worden gebruikt als een gemeenschappelijke referentie naar het ontwerp. Een combinatie van een zachte en harde systeembenadering leidt tot een conceptueel model, waarin het probleem wordt geformuleerd in termen van vereiste prestaties en proces structuren. Het logistiek systeem wordt gemodelleerd als een structuur van functies rond drie stromen: orders, materie en mensen en middelen. Het model groeit gedurende het ontwerpproject en biedt voortdurend ondersteuning bij de besluitvorming, steeds in relatie tot de systeemdoelstellingen. Dit PROces-PERformance model (PROPER model) maakt gebruik van een interdisciplinaire terminologie en maakt daardoor de communicatie tussen de verschillende disciplines mogelijk. Het PROPER model geeft alleen de structuur van een systeem weer; het tijdafhankelijke gedrag van het systeem wordt erdoor niet gemodelleerd. Dit gedrag is essentieel voor een correcte besluitvorming en in het algemeen wordt dit gesimuleerd met behulp van een computer. In de praktijk wordt simulatie vaak pas gebruikt aan het eind van een ontwerpproject; dan is echter een correctie van doelstellingen en/of besluiten onmogelijk of erg duur. In dit proefschrift wordt daarom aanbevolen om simulatie te gebruiken vanaf het begin van een project. Om dit te bereiken wordt het tijdafhankelijke gedrag ook op een interdisciplinaire wijze beschreven. Natuurlijke taal wordt gebruikt om processen te beschrijven zoals ze voorkomen in het PROPER model op elk aggregatiestratum