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ABSTRACT: Resources in large logistic networks are occasionally unavailable or malfunctioning. This implies that performability becomes an issue for quantitative analysis of logistic networks. Different time scales between failures and normal operation often justify the decomposition of a performability model into a single availability model that considers failures and recovery of resources and a family of performance models whose individual instances depend on the state of resources. In this paper, we present an approach that simulates a set of performance models independently and in a distributed manner on a network of workstations. We propose to optimize the achievable quality of results for a given total amount of CPU time by minimizing the confidence intervals for performability measures. This is possible by an adaptive assignment of CPU time to simulate those models whose results have the largest impact on the width of confidence intervals.
Parallel and Distributed Simulation, 2004. PADS 2004. 18th Workshop on; 06/2004
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ABSTRACT: In steady-state simulation the output data of the transient phase often causes a bias in the estimation of the steady-state results. A common advice is to cut off this transient phase. Finding an appropriate truncation point is a well-known problem and is still not completely solved. In this paper we consider two algorithms for the determination of the truncation point. Both are based on a technique which takes the definition of the steady-state phase more closely into consideration. The capabilities of the algorithms are demonstrated by comparisons with two methods most often used in practice.
Simulation Conference, 2003. Proceedings of the 2003 Winter; 01/2004
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F. Bause
Petri Nets and Performance Models, 2003. Proceedings. 10th International Workshop on; 10/2003
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ABSTRACT: This paper presents a toolset for modelling and analysing logistic networks. The toolset includes a graphical user interface
accommodating a “Process Chains” view. It supports model analysis by a variety of methods including simulative, algebraic
and numerical techniques. An object-based, hierarchical structure helps to keep track of large models. The hierarchy employs
the notion of function units which may include subordinate function units, where function units provide services to their
environments that are internally accomplished by calling services of subordinate function units. This point of view is very
much along the structures found in real world organisations. We describe and analyse a model of a supply chain to demonstrate
the capabilities of the toolset.
12/2001: pages 25-30;
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ABSTRACT: In this paper we introduce a general framework for the modeling, analysis and costing of logistic networks including supply chains (SCs). The employed modeling notation, the so-called Process Chain paradigm, is specically developed for the application eld of logistic networks which includes SCs. We view SCs as discrete event dynamic systems (DEDS) and apply corresponding simulative techniques in order to derive performance measures of the Process Chain model under investigation. For this purpose Process Chain models are automatically transformed into the input language of the simulation tool HIT. Subsequently, a cost accounting model using the performance measures is applied to obtain costs which are actually subject of interest. The usefulness and applicability of the approach is illustrated by a typical supply chain example. We investigate the impact of an additional SC channel between a manufacturer and web-consumers on the overall supply chain costs. 1 Supply Chain Modeling, ...
11/2001;
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ABSTRACT: This note considers the central activities of logistic network nodes which are typical examples of open systems exhibiting synchronisation aspects. We model a node's behaviour by means of a simple GSPN and show that a steady state distribution does not exist, irrespective of the parameters for the arrival streams. This effect shows an intrinsic problem of logistic networks and generally of open systems with synchronisation. We show additionally that imposing bounds on the population size is not helpful for analysis objectives like capacity planning. 1 Introduction Typical nodes of logistic networks are governed by transhipping processes. Consider one such node. Goods are delivered from outside, temporarily stored, and eventually collected and shipped out. Capacity planning is a standard task when designing such systems, and it appears a natural approach to start model-based analysis assuming an open and unlimited system. Hopefully results like mean buffer sizes, their varianc...
12/1999;
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ABSTRACT: Product from queueing Petri Nets (PQPNs) combine the results of
product form for Stochastic Petri Nets with the well-known BCMP results
in one modeling formalism and include them as special cases. In this
paper we establish an exact aggregation approach, based on the product
form, which extends Norton's theorem for aggregation in multi-class
product form Queueing Networks
Petri Nets and Performance Models, 1997., Proceedings of the Seventh International Workshop on; 07/1997
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ABSTRACT: : Queueing Petri Nets (QPNs) provide a powerful model world which integrates Queueing Nets (QNs), Coloured Petri Nets (CPNs) and Generalized Stochastic Petri Nets (GSPNs). QPN-Tool supports the specification of QPNs by a graphical interface and offers a variety of analysis algorithms exploiting Petri Net theory as well as Queueing Net theory. Petri Net theory is suitable for assessing functional system properties like liveness and boundedness of the underlying Petri Net (qualitative analysis). Queueing Net theory allows the computation of performance measures based on the steady state distribution of the embedded Markov chain (quantitative analysis). In summary: QPN-Tool combines a convenient description technique with capabilities of both qualitative and quantitative system assessments. 1 QPN - a Queueing Petri Net model world Basically, Queueing Petri Nets are Coloured Petri Nets whose places may be queues. More precisely, they allow for two types of places, ordinary plac...
11/1994;
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F. Bause
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ABSTRACT: System analysis is often needed with respect to both qualitative
and quantitative aspects. In recent decades, several formalisms have
been developed that attempt to combine these aspects in one description.
Present emphasis is on stochastic Petri nets. One disadvantage of these
formalisms is the difficulties when describing scheduling strategies
with Petri net elements. A new version of queuing Petri nets (QPNs),
which combines queuing networks and Petri nets, aiming at eliminating
these disadvantages is described. The new version also exhibits the
modeling of timed transitions and timeless queues for describing pure
scheduling mechanisms. QPNs are a superset of queueing networks and
(generalized stochastic) Petri nets. The analysis of QPNs is discussed,
and it is shown that efficient analysis techniques from Petri net theory
can be exploited for analysis of QPNs, thus supporting the general
objective of combining Petri net and queueing network formalisms
Petri Nets and Performance Models, 1993. Proceedings., 5th International Workshop on; 11/1993
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ABSTRACT: Zusammenfassung Die modellgestützte Gestaltung von Logistiknetzwerken steht im Zentrum der Arbeits-ziele des SFB 559. Im Bereich der Erfassung dynamischer Abläufe fußen die Arbeiten auf dem sog. Prozessketten-Paradigma. Der vorliegende Beitrag stellt eine neu entwi-ckelte Beschreibungsform für dynamische Modelle logistischer Systeme vor, welche einerseits die Vorstellungswelt des Prozessketten-Paradigmas weitestgehend beibe-hält, andererseits aber hinreichend präzise und vollständig ist, um eine automatische Übertragung zugehöriger Modelle in geeignete Simulationswerkzeuge zu erlauben. Der Beitrag beschreibt ferner die automatisierte Aufbereitung zugehöriger Modelle für effi-ziente nicht-simulative Analysetechniken aus den Bereichen der Warteschlangennetze und der stochastischen Petri-Netze. Die hochstrukturierte Natur des Beschreibungsfor-malismus ermöglicht darüber hinaus die Kombinationen unterschiedlicher Analysetech-niken und den Einsatz effizienzsteigernder Dekompositions-und Aggregierungsverfah-ren. Eine diesbezügliche (in der ersten Bewilligungsphase des SFB entwickelte) Tool-Umgebung wird skizziert, derzeitig bearbeitete Erweiterungen benannt.
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ABSTRACT: This paper shows that the aggregation and decomposition result known as Norton’s theorem for queueing networks can be extended to a general class of batch routing queueing networks with product-form solution that allows for multiple components to simultaneously release and receive (batches of) customers.
