International Journal of Advanced Manufacturing Technology | Year: 2011
The increasing complexity of manufacturing systems gives rise to the development of new formal methods allowing to handle their particularities. Petri nets are a powerful formalism for the specification and verification of concurrent systems including sequential systems and manufacturing systems. To deal with systems whose time issues become fundamental, different time Petri nets extensions have been developed in the literature, each one being dependent on the application considered. For the time critical systems, their correctness depends not only on the logic correctness but also on the time constraints. Timing issues are essential. In this paper, a new method of analysis and control for P-time Petri nets is proposed. It is based on the firing instant notion and exploits a constraint graph approach. © 2011 Springer-Verlag London Limited.
19th IEEE International Conference on Emerging Technologies and Factory Automation, ETFA 2014 | Year: 2014
This paper focuses on the problem of estimating the marking of a P-time labeled Petri net with partial information. The set of transitions is partitioned into those labeled with the empty string e called silent, as their firing cannot be detected, and the observable ones. The proposed approach is based on the observation of transitions labels thanks to the synthesis of a state observer obtained from the behavior of the untimed underlying Petri net. A procedure that, given an observed word (sequence of labels defined over a given alphabet) with their occurrence dates, allows to determine the set of states consistent with the considered observation is provided, under the assumption of non-Zenoness of the subnet induced by the set of unobservable transitions. Furthermore, a source of nondeterminism is added as the case of indistinguishable transitions (transitions sharing the same label) is also considered. The method relies on the schedulability analysis of particular firing sequences, namely the candidates firing sequences and does not require the building of the state classes graph although the time is modeled as intervals. © 2014 IEEE.
Journal Europeen des Systemes Automatises | Year: 2010
Petri nets are a powerful formalism for the specification and verification of concurrent systems such as sequential and manufacturing systems. To take into account efficiently the time parameter different extensions have been developed in the literature, each one being dependent on the application considered. In this paper, a new control technique for p-time Petri nets is proposed. It is based on the firing instant notion and it consists in determining a system of inequalities generated for a possible evolution (in terms of a feasible firing sequence for the untimed underlying Petri net) of the model considered. This system can be used to check reachability problems as well as evaluating the performances of the model considered and determining the associated control for a definite functioning mode. Furthermore, the proposed approach is not restricted to subclasses or safe Petri nets. © 2010 Lavoisier, Paris.
Stamatopoulos N.,Institute of Informatics and Telecommunications National Center for Scientific Research Demokritos |
Gatos B.,Institute of Informatics and Telecommunications National Center for Scientific Research Demokritos |
Louloudis G.,Institute of Informatics and Telecommunications National Center for Scientific Research Demokritos |
Pal U.,Indian Statistical Institute |
Proceedings of the International Conference on Document Analysis and Recognition, ICDAR | Year: 2013
This paper presents the results of the Handwriting Segmentation Contest that was organized in the context of the ICDAR2013. The general objective of the contest was to use well established evaluation practices and procedures to record recent advances in off-line handwriting segmentation. Two benchmarking datasets, one for text line and one for word segmentation, were created in order to test and compare all submitted algorithms as well as some state-of-the-art methods for handwritten document image segmentation in realistic circumstances. Handwritten document images were produced by many writers in two Latin based languages (English and Greek) and in one Indian language (Bangla, the second most popular language in India). These images were manually annotated in order to produce the ground truth which corresponds to the correct text line and word segmentation results. The datasets of previously organized contests (ICDAR2007, ICDAR2009 and ICFHR2010 Handwriting Segmentation Contests) along with a dataset of Bangla document images were used as training dataset. Eleven methods are submitted in this competition. A brief description of the submitted algorithms, the evaluation criteria and the segmentation results obtained from the submitted methods are also provided in this manuscript. © 2013 IEEE.
IEEE International Conference on Automation Science and Engineering | Year: 2011
This paper addresses the schedulability analysis of real-time systems modeled by P-Time Petri nets. The proposed approach is based on the consideration of the reachability graph of the (untimed) underlying Petri net of the studied model. The schedulability analysis is then conducted in two steps. Once a feasible firing sequence (called occurrence sequence) is highlighted, thanks to a firing instant based approach the timing constraints are added, yielding an inequality system representing its timing behavior. Thus, deciding whether a firing sequence is schedulable or not takes the form of the solution of a linear programming problem. Furthermore, the modification of a timing constraint does not alter the form of the obtained system, helping adjusting accurately timing properties in a specifications refinement purpose. © 2011 IEEE.