Stochastic Well-formed Net Research Articles

The Quantitative Assessment of Domino Effects Based on Stochastic Petri Nets

The quantitative analysis of “domino” effects is one of the main aspects of hazard assessment in chemical industrial park. This paper demonstrates the application of heterogeneous stochastic Petri net modeling techniques to the quantitative assessment of the probabilities of domino effects of major accidents in chemical industrial park. First, five events are included in the domino effect models of major accidents: pool fire, explosion, boiling liquid expanding vapour explosion (BLEVE) giving rise to a fragment, jet fire and delayed explosion of a vapour cloud. Then, the domino effect models are converted into Generalized Stochastic Petri net (GSPN) in which the probability of the domino effect is calculated automatically. The Stochastic Petri nets’ models, which are state-space based ones, increase the modeling flexibility but create the state-space explosion problems. Finally, in order to alleviate the state-space explosion problems of GSPN models, this paper employs Stochastic Wellformed Net (SWN), a particular class of High-Level (colored) SPN. To conduct a case study on a chemical industrial park, the probability of domino effects of major accidents is calculated by using the GSPN model and SWN model in this paper.

Performance evaluation of UML design with Stochastic Well-formed Nets

The paper presents a method to compute performance metrics ( response time, sojourn time, throughput) on Unified Modeling Language design. The method starts with UML design annotated according to the UML Profile for Schedulability, Performance and Time. The UML design is transformed into a performance model where to compute the referred metrics. Being the performance model a Stochastic Well-formed Net, the method is enabled to analyze systems where the object identities are relevant as well as those where they are not. A complete case study reveals how to apply the method and its usefulness.

Using a Stochastic Well-formed Net model for assessing a decentralized approach to configuration management

Traditional support tools for software engineers, normally based on a client–server architecture, are unsuitable to deal with the new issues emerging from the current (and future) cooperative work scenarios (where connectivity is intrinsically transient, the number of interacting partners dynamically changes, etc.). This paper presents a quantitative assessment of a fully decentralized, peer-to-peer, cooperative infrastructure. Stochastic Well-formed Nets (SWNs) modeling the new peer-to-peer architecture, and a traditional (client–server) one, are developed and analyzed: we used SWNs for their ability to directly exploit the symmetries intrinsically present in the modeled systems in order to reduce the complexity of analysis/simulation. The goal is to compare the impact of the two alternative protocols on the collaborative work. The paper focuses on methodological issues concerning choice of an appropriate model abstraction level, adoption of a compositional modeling approach, and mainly, management of model solution complexity. Some performance figures of interest (selected among a number) are also presented and discussed.