Results 1  10
of
62
Diagnosis of Asynchronous Discrete Event Systems, a Net Unfolding Approach
 IEEE TRANS. ON AUTOMATIC CONTROL
, 2001
"... In this paper we formulate asynchronous diagnosis by means of hidden state history reconstruction, from alarm observations. We follow a socalled true concurrency approach, in which no global state and no global time is available. Instead, we use only local states in combination with a partial order ..."
Abstract

Cited by 91 (28 self)
 Add to MetaCart
(Show Context)
In this paper we formulate asynchronous diagnosis by means of hidden state history reconstruction, from alarm observations. We follow a socalled true concurrency approach, in which no global state and no global time is available. Instead, we use only local states in combination with a partial order model of time, in which local events are ordered if they are either generated on the same site, or related via some causality relation. Our basic mathematical tool is that of net unfoldings originating from the Petri net research area. This study was motivated by the problem of event correlation in telecommunications network management.
Markov Nets: Probabilistic Models for distributed and concurrent systems
 IEEE Transactions on Automatic Control
, 2001
"... For distributed systems, i.e. large networked complex systems, there is a drastic difference between a local view and knowledge of the system, and its global view. Distributed systems have local state and time, but do not possess global state and time in the usual sense. In this paper, motivated by ..."
Abstract

Cited by 39 (17 self)
 Add to MetaCart
For distributed systems, i.e. large networked complex systems, there is a drastic difference between a local view and knowledge of the system, and its global view. Distributed systems have local state and time, but do not possess global state and time in the usual sense. In this paper, motivated by the monitoring of distributed systems and in particular of telecommunications networks, we develop Markov nets as an extension of Markov chains and hidden Markov models (Hmm) for distributed and concurrent systems. By a concurrent system, we mean a system in which components may evolve independently, with sparse synchronizations. We follow a socalled true concurrency approach, in which neither global state nor global linear time are available. Instead, we use only local states in combination with a partial order model of time. Our basic mathematical tool is that of Petri net unfoldings. Keywords : discrete event systems, stochastic Petri nets, unfoldings. 1 Motivations Distributed network...
Distributed Diagnosis of discreteevent systems using Petri net unfoldings
 Proc. of ICATPN 2003, volume 2679 of LNCS
, 2003
"... Abstract. The problem of detecting and isolating fault events in dynamic systems modeled as discreteevent systems is considered. The modeling formalism adopted is that of Petri nets with labeled transitions, where some of the transitions are labeled by different types of unobservable fault events ..."
Abstract

Cited by 28 (4 self)
 Add to MetaCart
(Show Context)
Abstract. The problem of detecting and isolating fault events in dynamic systems modeled as discreteevent systems is considered. The modeling formalism adopted is that of Petri nets with labeled transitions, where some of the transitions are labeled by different types of unobservable fault events. The Diagnoser Approach for discreteevent systems modeled by automata developed in earlier work is adapted and extended to online fault diagnosis of systems modeled by Petri nets, resulting in a centralized diagnosis algorithm based on the notion of “Petri net diagnosers”. A distributed version of this centralized algorithm is also presented. This distributed version assumes that the Petri net model of the system can be decomposed into two placebordered Petri nets satisfying certain conditions and that the two resulting Petri net diagnosers can exchange messages upon the occurrence of observable events. It is shown that this distributed algorithm is correct in the sense that it recovers the same diagnostic information as the centralized algorithm. The distributed algorithm provides an approach for tackling fault diagnosis of large complex systems. 1
Hybrid systems diagnosis
 In Proceedings of Hybrid Systems: Computation and Control, Lecture Notes in Computer Science
, 2000
"... Abstract. This paper reports on an ongoing project to investigate techniques to diagnose complex dynamical systems that are modeled as hybrid systems. In particular, we examine continuous systems with embedded supervisory controllers that experience abrupt, partial or full failure of component devi ..."
Abstract

Cited by 26 (4 self)
 Add to MetaCart
(Show Context)
Abstract. This paper reports on an ongoing project to investigate techniques to diagnose complex dynamical systems that are modeled as hybrid systems. In particular, we examine continuous systems with embedded supervisory controllers that experience abrupt, partial or full failure of component devices. We cast the diagnosis problem as a model selection problem. To reduce the space of potential models under consideration, we exploit techniques from qualitative reasoning to conjecture an initial set of qualitative candidate diagnoses, which induce a smaller set of models. We refine these diagnoses using parameter estimation and model fitting techniques. As a motivating case study, we have examined the problem of diagnosing NASA’s Sprint AERCam, a small spherical robotic camera unit with 12 thrusters that enable both linear and rotational motion. 1
Distributed State Reconstruction for Discrete Event Systems
, 2000
"... We consider a discrete event dynamic system (DEDS) obtained by the parallel composition of several subsystems. Each subsystem can be seen as a standard stochastic DEDS. The composed system is provided with true concurrency semantics that emphasize concurrent behaviors of the subsystems. For these ..."
Abstract

Cited by 21 (9 self)
 Add to MetaCart
We consider a discrete event dynamic system (DEDS) obtained by the parallel composition of several subsystems. Each subsystem can be seen as a standard stochastic DEDS. The composed system is provided with true concurrency semantics that emphasize concurrent behaviors of the subsystems. For these semantics, a trajectory appears as a partial order of events. For simplicity, we focus on the case of a global system composed of only two subsystems. We assume that firings in each subsystem are collected by a local sensor, which yields a sequence of transition labels (or events). The objective is to recover the most likely global trajectory of the system from the two (asynchronous) sequences of observations. This is an almost standard hidden state estimation problem, amenable to the clasical Viterbi algorithm. We propose a solution in which this global trajectory is built recursively by two asynchronously cooperating "players, " each one being in charge of one subsystem. These two players run local Viterbi algorithms based on local states of the subsystems, plus some coordination information. This supervising architecture is particularly suited to large modular systems and is currently being applied to the distributed monitoring (and fault diagnosis) of telecommunication networks.
On the Effect of Communication Delays in Failure Diagnosis of Decentralized Discrete Event Systems
, 2001
"... We study the eect of communication delays on the performance of a coordinated decentralized architecture for failure diagnosis of untimed discrete event systems. The architecture consists of local sites communicating with a coordinator that is responsible for diagnosing the failures occurring in the ..."
Abstract

Cited by 20 (0 self)
 Add to MetaCart
We study the eect of communication delays on the performance of a coordinated decentralized architecture for failure diagnosis of untimed discrete event systems. The architecture consists of local sites communicating with a coordinator that is responsible for diagnosing the failures occurring in the system. A protocol that realizes the architecture is dened by the diagnostic information generated at the local sites, the communication rules used by the local sites, and the decision rule used by the coordinator to infer the occurrence of failures. Our prior work [6] has addressed the performance of a set of protocols under the assumption that messages sentfromvarious local sites to the coordinator are received in the order in which they are sent globally. In this work we relax the abovementioned assumption. We modify the coordinator's decision rule for one of the protocols analyzed in [6]toaccount for the reception of out of order messages at the coordinator's site. We discover conditi...
ModelBased Monitoring of ComponentBased Software Systems
"... The development of componentbased software systems opens the possibility of using modelbased diagnosis techniques for large software systems. We have developed a simple monitoring system based on the modeling of the external behavior of software components by Petri nets. With each component is ass ..."
Abstract

Cited by 15 (0 self)
 Add to MetaCart
The development of componentbased software systems opens the possibility of using modelbased diagnosis techniques for large software systems. We have developed a simple monitoring system based on the modeling of the external behavior of software components by Petri nets. With each component is associated a local controller which observes the messages received and sent by the component and compares them with the specified behavior. As the components interact, information is collected on error emission and time constraint violation to infer indicators about the state of components.
Monitoring web service networks in a modelbased approach
 In 3rd IEEE European Conference on Web Services (ECOWS05
"... Archives des publications du CNRC (NPArC) ..."
(Show Context)
Monitoring distributed systems with distributed algorithms
 In Proc of the 2002 IEEE Conf. on Decision and Control, 411–416, Dec. 2002, Las Vegas
"... This paper proposes a framework to process large distributed systems by parts, through distributed algorithms. We consider distributed (discrete event) systems as the combination of elementary components. Each component defines dynamics on several state variables, and the composition is simply defin ..."
Abstract

Cited by 13 (7 self)
 Add to MetaCart
(Show Context)
This paper proposes a framework to process large distributed systems by parts, through distributed algorithms. We consider distributed (discrete event) systems as the combination of elementary components. Each component defines dynamics on several state variables, and the composition is simply defined by sharing variables. The compound system is asynchronous: each component evolves with its own clock, and exchanges information with its neighbors by means of the shared variables. An interaction graph can be associated to such a compound system: two components are neighbors of each other as soon as they share one (or more) variables. This structure is reminiscent of Bayesian networks, or Markov random fields, which use a graph to display dependencies between random variables. The parallel can actually be pushed quite far. In this paper we show that a large family of modular algorithms developped for Markov fields, in order to solve problems like maximum likelihood state estimation, can be translated into distributed algorithms to monitor large distributed dynamic systems. 1
Decentralized Failure Diagnosis with Asynchronous Communication between Supervisors
, 2001
"... Decentralized failure diagnosis problems arise in communication networks. Network operators require automated tools to isolate failures that need immediate attention. Failure notification is often accompanied with local timing information, although the presence of a global clock is not guaranteed. A ..."
Abstract

Cited by 11 (1 self)
 Add to MetaCart
Decentralized failure diagnosis problems arise in communication networks. Network operators require automated tools to isolate failures that need immediate attention. Failure notification is often accompanied with local timing information, although the presence of a global clock is not guaranteed. A timed discreteevent system for decentralized failure diagnosis is proposed. Additionally, the model allows asynchronous communication between decentralized diagnosers. The problem is treated whether an observor map of a diagnoser factors over a timed discreteevent system with a finite state set.