Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497859
Huixia Liu, Weimin Wu, H. Su, Hong-yong Yang
Computational complexity is one of most important criteria in evaluating the performance of deadlock control methods. Based on Petri net models, a polynomial deadlock avoidance method is addressed for a class of flexible manufacturing systems (FMSs) with key resources. It is first proved that there are three kinds of reachable markings in these FMSs: safe ones, deadlock, and secondary deadlock. Second, an algorithm with polynomial complexity to determine the safety of a new marking resulting from a safe one is presented. It adopts a one-step look-ahead method and two-step look-ahead one to prohibit the firings of transitions that result in deadlock and secondary one, respectively. Thus, a polynomial deadlock avoidance policy for a class of FMSs with key resources is established. An illustrative example is provided to demonstrate the efficiency of the proposed method.
{"title":"A polynomial complexity deadlock avoidance method for a class of flexible manufacturing systems","authors":"Huixia Liu, Weimin Wu, H. Su, Hong-yong Yang","doi":"10.1109/WODES.2016.7497859","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497859","url":null,"abstract":"Computational complexity is one of most important criteria in evaluating the performance of deadlock control methods. Based on Petri net models, a polynomial deadlock avoidance method is addressed for a class of flexible manufacturing systems (FMSs) with key resources. It is first proved that there are three kinds of reachable markings in these FMSs: safe ones, deadlock, and secondary deadlock. Second, an algorithm with polynomial complexity to determine the safety of a new marking resulting from a safe one is presented. It adopts a one-step look-ahead method and two-step look-ahead one to prohibit the firings of transitions that result in deadlock and secondary one, respectively. Thus, a polynomial deadlock avoidance policy for a class of FMSs with key resources is established. An illustrative example is provided to demonstrate the efficiency of the proposed method.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128339296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497874
C. Hadjicostis, C. Seatzu
We consider the problem of decentralized state estimation, where two or more observation sites send information to a coordinator who aims to determine the set of possible current states of a given discrete event system (DES). More specifically, we consider a DES (modeled as a nondeterministic finite automaton) whose underlying activity is partially observed at multiple observation sites that can gather information about different subsets of events. When these sites report to the coordinator the sequences of observations that they have recorded, the goal is to fuse this information and infer the possible current states of the given system. We discuss an efficient recursive algorithm that can perform this task with complexity that is captured by the product of the lengths of the observation sequences reported by the observation sites.
{"title":"Decentralized state estimation in discrete event systems under partially ordered observation sequences","authors":"C. Hadjicostis, C. Seatzu","doi":"10.1109/WODES.2016.7497874","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497874","url":null,"abstract":"We consider the problem of decentralized state estimation, where two or more observation sites send information to a coordinator who aims to determine the set of possible current states of a given discrete event system (DES). More specifically, we consider a DES (modeled as a nondeterministic finite automaton) whose underlying activity is partially observed at multiple observation sites that can gather information about different subsets of events. When these sites report to the coordinator the sequences of observations that they have recorded, the goal is to fuse this information and infer the possible current states of the given system. We discuss an efficient recursive algorithm that can perform this task with complexity that is captured by the product of the lengths of the observation sequences reported by the observation sites.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"144 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116405093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497858
Yan Yang, Hesuan Hu
One of the major concerns facing the modern engineering community is the development of efficient deadlock control policies for manufacturing systems, primarily because of the non-tractability and non-scalability of most existing control policies. Aiming to bring all active process instances to completion, this paper focuses on distributed control of systems integrating assembly operations with flexible routes. Each step's execution depends on the search of a feasible event sequence, leading the currently-active process instance from its current place to its nearest global critical place. In the context of this search, feedback information on the current resource allocation status, combined with information about future process resource requirements, are used to keep the currently-active process instance away from deadlock states. As we shall see in the following, such an on-line and real-time predictive control policy makes improvements on many perspectives such as computational complexity and system performance.
{"title":"Backward conflict free systems with resources and their distributed control using Petri nets","authors":"Yan Yang, Hesuan Hu","doi":"10.1109/WODES.2016.7497858","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497858","url":null,"abstract":"One of the major concerns facing the modern engineering community is the development of efficient deadlock control policies for manufacturing systems, primarily because of the non-tractability and non-scalability of most existing control policies. Aiming to bring all active process instances to completion, this paper focuses on distributed control of systems integrating assembly operations with flexible routes. Each step's execution depends on the search of a feasible event sequence, leading the currently-active process instance from its current place to its nearest global critical place. In the context of this search, feedback information on the current resource allocation status, combined with information about future process resource requirements, are used to keep the currently-active process instance away from deadlock states. As we shall see in the following, such an on-line and real-time predictive control policy makes improvements on many perspectives such as computational complexity and system performance.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130899748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497835
J. Vilela, P. Pena
Finite-state automata and Supervisory Control Theory have been used to model and solve job-shop scheduling and planning problems. However, even if it seems to be easier to work with DFA and SCT, this solution will suffer with “the curse of dimensionality”, which can cause state explosion when the system becomes bigger and more complex. This paper presents a set of sufficient conditions that allow to work with abstractions of the supervisor, instead of the supervisor itself, as the search universe to solve a planning problem. Such abstraction is the natural projection of the supervisor into the set of controllable events and it should satisfy the observer property. This abstraction is smaller then the original automaton, which reduces the search universe for the optimization algorithms. Also, we present a set of conditions for the model of the system and specifications that will results on the satisfaction of the observer property.
{"title":"Supervisor abstraction to deal with planning problems in manufacturing systems","authors":"J. Vilela, P. Pena","doi":"10.1109/WODES.2016.7497835","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497835","url":null,"abstract":"Finite-state automata and Supervisory Control Theory have been used to model and solve job-shop scheduling and planning problems. However, even if it seems to be easier to work with DFA and SCT, this solution will suffer with “the curse of dimensionality”, which can cause state explosion when the system becomes bigger and more complex. This paper presents a set of sufficient conditions that allow to work with abstractions of the supervisor, instead of the supervisor itself, as the search universe to solve a planning problem. Such abstraction is the natural projection of the supervisor into the set of controllable events and it should satisfy the observer property. This abstraction is smaller then the original automaton, which reduces the search universe for the optimization algorithms. Also, we present a set of conditions for the model of the system and specifications that will results on the satisfaction of the observer property.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115864844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497829
W. M. Boussahel, Georg Frey
Cost optimization is a main concern of the industry nowadays and reducing the total energy input is one of the main ways to achieve it. Modeling through discrete event systems is a powerful tool to model complex human made systems often encountered in the manufacturing and model checkers offer a framework for the evaluation and optimization of such systems. A formalism is presented in the present paper to define a discrete version of Priced Timed Automata in the model checker PRISM by using an extension to discrete automata. Priced Timed Automata have been introduced as a formal way to study real time continuous systems. However, PRISM is a tool conceived for discrete automata but cannot handle the continuous priced automata directly due to its high restrictions in using the clock variables. The presented formalism offers an approach of modelling that gets around these restrictions.
{"title":"Priced discrete Automata for modeling energy efficient manufacturing systems","authors":"W. M. Boussahel, Georg Frey","doi":"10.1109/WODES.2016.7497829","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497829","url":null,"abstract":"Cost optimization is a main concern of the industry nowadays and reducing the total energy input is one of the main ways to achieve it. Modeling through discrete event systems is a powerful tool to model complex human made systems often encountered in the manufacturing and model checkers offer a framework for the evaluation and optimization of such systems. A formalism is presented in the present paper to define a discrete version of Priced Timed Automata in the model checker PRISM by using an extension to discrete automata. Priced Timed Automata have been introduced as a formal way to study real time continuous systems. However, PRISM is a tool conceived for discrete automata but cannot handle the continuous priced automata directly due to its high restrictions in using the clock variables. The presented formalism offers an approach of modelling that gets around these restrictions.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116476637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497881
Soraia Moradi, L. Hardouin, J. Raisch
The topic of this paper is the modeling and control of a class of timed Petri nets with resource sharing problems in a dioid framework. We first introduce a signal which denotes the number of resources available for each competing subsystem at each instant of time. Based on this signal, the overall system is modeled in min-plus algebra. Using residuation theory, an optimal control policy is developed, where optimality is in the sense of a lexicographical order reflecting the chosen prioritization of subsystems.
{"title":"Modeling and control of resource sharing problems in dioids","authors":"Soraia Moradi, L. Hardouin, J. Raisch","doi":"10.1109/WODES.2016.7497881","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497881","url":null,"abstract":"The topic of this paper is the modeling and control of a class of timed Petri nets with resource sharing problems in a dioid framework. We first introduce a signal which denotes the number of resources available for each competing subsystem at each instant of time. Based on this signal, the overall system is modeled in min-plus algebra. Using residuation theory, an optimal control policy is developed, where optimality is in the sense of a lexicographical order reflecting the chosen prioritization of subsystems.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123698963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497882
Hakima Hamri, R. Kara, S. Amari
The focus of this paper is to synthesise an optimal control law that allows to track a desired trajectory with respect to the constraints both on the control and state vectors for a class of Discrete Event Systems (DESs). For this, a geometric approach of a model predictive control is extended to a class of DESs modelled by P-time event graphs in the standard algebra using the dater equations. The use of the concept of (A, B)-invariance allows us to obtain the polyhedral parametric constraints. The constrained parametric model predictive control leads for a multiparametric quadratic programming (MP-QP) for which the solution is a feedback Piece-Wise Affine (PWA) control defined for different feasible regions.
{"title":"Multiparametric predictive control for a class of Discrete Event Systems","authors":"Hakima Hamri, R. Kara, S. Amari","doi":"10.1109/WODES.2016.7497882","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497882","url":null,"abstract":"The focus of this paper is to synthesise an optimal control law that allows to track a desired trajectory with respect to the constraints both on the control and state vectors for a class of Discrete Event Systems (DESs). For this, a geometric approach of a model predictive control is extended to a class of DESs modelled by P-time event graphs in the standard algebra using the dater equations. The use of the concept of (A, B)-invariance allows us to obtain the polyhedral parametric constraints. The constrained parametric model predictive control leads for a multiparametric quadratic programming (MP-QP) for which the solution is a feedback Piece-Wise Affine (PWA) control defined for different feasible regions.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122448945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497875
M. Ibrahim, Jun Chen, Ratnesh Kumar
Unlike information, behaviors cannot be encrypted and may instead be protected by providing covers that generate indistinguishable observations from behaviors needed to be kept secret. Such a scheme may still leak information about secrets due to statistical difference between the occurrence probabilities of the secrets and their covers. Jensen-Shannon Divergence (JSD) is a possible means of quantifying statistical difference between two distributions and was used to measure such information leak as in our earlier work [1]. This paper studies secrecy quantification in stochastic partially-observed discrete event systems in the presence of distributed collusive attackers/observers, each with its own local partial observability, generalizing the setting of single observer in [1]. The local observers collude and exchange their observations over communication channels that introduce bounded delays. We propose a method to compute the JSD-based secrecy measure in this distributed setting by introducing bounded-delay channel models to extend the system model to capture the effect of exchange of observations, and to measure the distributed secrecy loss.
{"title":"Quantification of distributed secrecy loss in stochastic discrete event systems under bounded-delay communications","authors":"M. Ibrahim, Jun Chen, Ratnesh Kumar","doi":"10.1109/WODES.2016.7497875","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497875","url":null,"abstract":"Unlike information, behaviors cannot be encrypted and may instead be protected by providing covers that generate indistinguishable observations from behaviors needed to be kept secret. Such a scheme may still leak information about secrets due to statistical difference between the occurrence probabilities of the secrets and their covers. Jensen-Shannon Divergence (JSD) is a possible means of quantifying statistical difference between two distributions and was used to measure such information leak as in our earlier work [1]. This paper studies secrecy quantification in stochastic partially-observed discrete event systems in the presence of distributed collusive attackers/observers, each with its own local partial observability, generalizing the setting of single observer in [1]. The local observers collude and exchange their observations over communication channels that introduce bounded delays. We propose a method to compute the JSD-based secrecy measure in this distributed setting by introducing bounded-delay channel models to extend the system model to capture the effect of exchange of observations, and to measure the distributed secrecy loss.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122678613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497836
Yijie Peng, M. Fu, Jianqiang Hu
We propose a generalized likelihood ratio estimator for the distribution sensitivity in a general framework. Applications on quantile sensitivity, sensitivity of distortion risk measure, and gradient-based maximum likelihood estimation are put together under a single umbrella, and addressed uniformly by the proposed estimator. Numerical experiments substantiate the efficiency of the new method.
{"title":"Estimating distribution sensitivity using generalized likelihood ratio method","authors":"Yijie Peng, M. Fu, Jianqiang Hu","doi":"10.1109/WODES.2016.7497836","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497836","url":null,"abstract":"We propose a generalized likelihood ratio estimator for the distribution sensitivity in a general framework. Applications on quantile sensitivity, sensitivity of distortion risk measure, and gradient-based maximum likelihood estimation are put together under a single umbrella, and addressed uniformly by the proposed estimator. Numerical experiments substantiate the efficiency of the new method.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126417737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-05-01DOI: 10.1109/WODES.2016.7497825
M. P. Fanti, A. M. Mangini, G. Pedroncelli, W. Ukovich
This paper deals with two basic design problems that incur in a modern city transportation strategy, i.e., the Electric Car Sharing System (ECSS). Modelling the system in a modular Timed Petri Net (TPN) framework, the optimal fleet size and the number of charging positions of the ECSS are determined by a simulation analysis. The ECSS dynamics is described by taking into account fully charged, partially charged and out of power electric vehicles. Moreover, TPNs allow taking into account some particular events, like specific user flows in different time bands or the exit of the customers from the station after waiting for the availability of electric cars. A simulation study points out the effectiveness of the proposed design strategy.
{"title":"A Petri Net model for fleet sizing of Electric Car Sharing Systems","authors":"M. P. Fanti, A. M. Mangini, G. Pedroncelli, W. Ukovich","doi":"10.1109/WODES.2016.7497825","DOIUrl":"https://doi.org/10.1109/WODES.2016.7497825","url":null,"abstract":"This paper deals with two basic design problems that incur in a modern city transportation strategy, i.e., the Electric Car Sharing System (ECSS). Modelling the system in a modular Timed Petri Net (TPN) framework, the optimal fleet size and the number of charging positions of the ECSS are determined by a simulation analysis. The ECSS dynamics is described by taking into account fully charged, partially charged and out of power electric vehicles. Moreover, TPNs allow taking into account some particular events, like specific user flows in different time bands or the exit of the customers from the station after waiting for the availability of electric cars. A simulation study points out the effectiveness of the proposed design strategy.","PeriodicalId":268613,"journal":{"name":"2016 13th International Workshop on Discrete Event Systems (WODES)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117101752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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