Petri Net Design Research Articles

Verification of cryptocurrency consensus protocols: reenterable colored Petri net model design

The reliability of consensus protocols establishes the basis for cryptocurrency cybersecurity. Formal and simulation techniques are appreciated for the verification of proof-of-work agreement protocols, because the formal techniques development process frequently requires a series of assumptions, leading to somewhat unrealistic models. A conventional colored Petri net model, presented by the authors in a previous study, allowed us to refine the Keller and Böhme consensus protocol by applying the simulation technique. In this study, we developed a reenterable colored Petri net model representing a general construct for model-driven development and refinement of consensus protocols and the corresponding software. A considerable benefit of a reenterable model is the invariance of its structure with respect to the net topology, number of attached nodes, and parameters of their software and hardware, which are represented as the marking of dedicated places. Switching of topology tags associated with dynamic objects represents the basic principle of reenterable model functioning. It is shown that, having the same characteristics, in bounds of admissible error of some 2-3%, the reenterable model results in 6 times speed-up of the simulation process and a drastic decrease in time for model editing, especially when the number of nodes exceeds a hundred. Thus, a reenterable model is a valuable complement to possible formal models that allows us to obtain express-evaluations of characteristics in a rather short time and with an acceptable level of adequacy.

МОДЕЛИРОВАНИЕ СИСТЕМЫ ОЧИСТКИ СТОЧНЫХ ВОД ЖИВОТНОВОДЧЕСКИХ ФЕРМ НА ОСНОВЕ СЕТЕЙ ПЕТРИ

The development of animal husbandry on an industrial basis causes a sharp increase in the amount of highly polluted wastewater, the purification and disinfection of which is one of the most important tasks when deciding on their use in agriculture as fertilizer or discharge into reservoirs or irrigation fields. The effectiveness of such systems is achieved with the help of new ways of processing information and mathematical characteristics of technology processes. Based on the study of the main methods of creating discrete chemical and technological systems (CTS), the expediency of using the design of Petri nets (SP) to simulate the process of wastewater treatment of livestock farms (OSWF) was developed. To characterize the system, we use N–schemes, which are based on the mathematical system of the joint venture, which can form a network structure both in analytical form for automating work during analysis, and in graphical form to create visibility of the created model. Analyzing technological and chemical processes, it is important to take into account the formality condition of N–circuits, which assumes that the circuits do not take the properties of simulated systems in time, since the timing of the transition is taken to be zero. We took into account these conditions and proposed updated Petri nets that are focused on the analysis and simulation of discrete CTS, by changing the time delay of labels on transitions and positions, as well as by enabling transitions that are in priority. We have created a model in the form of a modified updated Petri net (SME). With the help of SCADA TRACE MODE technologies, we have developed a whole software package for the control system in the process of OSWF. This system can perform dispatching monitoring of the main parts of the control apparatus, as well as stop and analyze and monitor its condition, this is feasible both in general and within the framework of forecasting the occurrence of emergency situations.

Logistic Support Architecture with Petri Net Design in Cloud Environment for Services and Profit Optimization

Cloud computing refers to both the applications delivered as services over the Internet and hardware and system software in the cloud server farm that provides those services. The research on server backup of cloud server farm appears to be an important issue of cloud computing economics. Optimal logistic policy should be considered to be a profit-oriented framework simultaneously for providing qualified service to cloud users while the whole cloud center is under construction. The kernel point of the proposed approach is that a novel design pattern is developed for approaching optimal profit on logistics using the finite-source queuing theory. To model the proposed approach for qualitative analysis, a Petri Net model was developed to configure all relevant system aspects in a concise fashion. On quantitative work, a comprehensive mathematical analysis on profit pattern has been made in detail. Relevant simulations have also been conducted to validate the proposed optimization model. The design illustration is presented to demonstrate engineering application scenario in cloud environment, hence the proposed approach indeed provides a feasibly profit-oriented framework to meet logistic economy.

Wi-Bio: management policy aimed at the establishment of networks for patient monitoring using IEEE 802.11

INTRODUCTION: Patient monitoring will tend to decline in the coming years due to a shortage of physical and human resources in hospitals. Therefore, several studies define alternatives to improve patient monitoring using wireless networks. In these studies, a wireless network is used to transfer data generated by medical sensors without interacting with the traffic in the data network of the hospital. However, this approach should be avoided because there are demands for integration between user applications and patient monitoring. Therefore, this paper defines a patient monitoring system, called Wi-Bio, directed to the establishment of IEEE 802.11 networks that allows traffic generated by user applications. METHODS: The formal validation of Wi-Bio was made through the design of Petri nets, and performance analysis was performed through simulations of the Network Simulator 2 tool. The adoption of this approach is justified by the fact that Petri nets allow verification of logical correctness of the designed systems, while simulations allow behavioral analysis of Wi-Bio in overload scenarios where many patients are monitored. RESULTS: The results confirmed the validity of the designed Petri nets and showed that Wi-Bio is able to accomplish the temporal goals imposed by medical sensors, thereby promoting efficient integration of traffic present in the data network and the patient monitoring network. CONCLUSION: As described, Wi-Bio fulfilled its objectives and motivates future studies aimed at complementing the obtained results.

Lifetime elongation of ad hoc networks under flooding attack using power-saving technique

Without the management of centralized unit, mobile ad hoc networks (MANETs) are vulnerable to security threats from flooding attacks launched through compromised nodes or intruders. When a source node needs a data session with a destination node, it disseminates a route request (RREQ) message to its neighbors in a hop-by-hop manner. One crucial type of flooding attacks called RREQ flooding appears to be inevitably proliferated in wireless networks. In the RREQ flooding attack, attackers would launch massive RREQ packets with out-of-domain IP address as its destination node. The forwarding services conducted by all intermediate nodes exhaust their energy and processing resources. The proposed approach can suppress redundant RREQ packets using the co-operation of destination node and neighbor nodes within one-hop range of the attacking node. A Petri Net design was developed to model the proposed approach and configure all relevant system aspects in a concise fashion for qualitative analysis. From quantitative viewpoint, relevant network simulations were conducted to validate the proposed scheme using a NS2 network simulator. The experimental result reveals that the proposed power-saving technique can be applied to economically and effectively elongate the operational lifetime of MANETs under flooding attack.

Control Design of Timed Petri Nets via Model Predictive Control with Continuous Petri Nets

This paper addresses the problem of control design for T-Timed Discrete Petri Net (T-TDPN) systems. The problem is studied using Model Predictive Control (MPC) and Timed Continuous Petri Net (TCPN) systems. Our goal is to find an approach which determines, in a systematic way, the firing sequence that drives a T-TDPN from an initial marking to a desired one. Since it had been proved that the MPC is an attractive feedback strategy in the case of TCPN under infinite server semantics and that this latter represents a good fluid approximation of the Discrete Event Systems, the proposed method deals with MPC applied on the TCPN equivalent to the discrete one and then, from the obtained results, deduces the firing sequence and computes the discrete markings.

An Optimization Approach to Improved Petri Net Controller Design for Automated Manufacturing Systems

Sensors and actuators are two indispensable parts in the paradigm of feedback control. Their implementation cost should be properly evaluated and constrained. In the previous work, a Petri net monitor with the least cost is synthesized through integer programming formulation. Despite its technical correctness, the existing method may lead to undesirable results when the net structure contains some shared or unshared resource places of a manufacturing-oriented net model. A necessary and sufficient condition is established to show that certain structures can lead to deadlock-prone supervisors. An efficient algorithm is developed to identify such structures. Furthermore, it is shown that if one can identify such structures at the initial stage, it is possible to achieve desirable controllers for the original systems. The theoretical correctness of the proposed algorithm is discussed. A manufacturing example is provided to illustrate the proposed approach.

Design and Identification of Stochastic and Deterministic Stochastic Petri Nets

In this paper, we consider the identification problem of stochastic and deterministic stochastic Petri nets (PNs). The approach herein proposed consists of inferring a PN structure and identifying its parameters. Hence, the first step leads to the synthesis of a PN structure with the measurable sequence of events and states. This approach determines the measurable part and estimates the nonmeasurable part of the PN to be established. Once both parts are obtained, the PN structure and the initial marking of the nonmeasurable places are obtained thanks to the integer linear programming technique. In the second step of this approach, the parameters of the obtained model are estimated. Stochastic and deterministic stochastic PNs with deterministic and exponentially distributed transition durations are considered. A systematic identification method is proposed based on event sequences that are recorded by supervision systems. This method is based on a Markov model whose state space is isomorphic to the reachability graph of the untimed PN model.

A Petri net design of FPGA-based controller for a class of nuclear I&C systems

This study is concerned with a FPGA-based controller design for the lack of FPGA-based solutions in the nuclear industry. An efficient design procedure is proposed to achieve simpler and affordable verification and validation (V&V) of system efforts by explicitly modeling the interactions among processes. In the present approach, both of state diagram (SD) concept and Petri nets (PNs) are used to model the concurrent processes. An illustrative example of automatic seismic trip system (ASTS) is provided. Synthesis results demonstrate that the proposed design is feasible and easy to implement.

Self-adapting recovery nets for policy-driven exception handling in business processes

In this paper, we propose Self-Adapting Recovery Net (SARN), an extended Petri net model, for specifying exceptional behavior in business processes. SARN adapts the structure of the underlying Petri net at run time to handle exceptions while keeping the Petri net design easy. The proposed framework caters for the specification of high-level recovery policies that are incorporated either with a single task or a set of tasks, called a Recovery Region. These recovery policies are generic directives that model exceptions at design time together with a set of primitive operations used at run time to handle the occurrence of exceptions. We identified a set of recovery policies that are useful and commonly needed in many practical situations. A tool has been developed to illustrate the viability of the proposed exception handling technique.

Controller Design of DES Petri Nets with Mixed Constraint

The problem of constructing a Petri net feedback controller, which enforces the conjunction of a set of linear inequalities on the reachable marking of the place and transition modeled by Petri net, is discussed. A new method of controller design with mixed constraint is presented, and a net reduction technique of Petri net fuses all the constrained places into one place whose marking is equal to the sum of the markings of the constrained places, and then compared with the constrained transitions. The net reduction eases the design of controller and holds remarkable advantages especially for systems with large scale. The method is proved to be simpler and more efficient than the method presented by Yamalidou, et al, using an applied case used by Yamalidou, et al.

Optimal Legal Firing Sequence of Petri Nets Using Linear Programming

Petri nets (PNs) are a reliable graphical and mathematical modeling tool for the formal modeling and validation of systems (W. Reisig, A Primer in Petri Net Design, Springer-Verlag: Berlin, Heidelberg, 1992). Applications of PNs include discrete event dynamic systems (DEDS) that are recognized as being concurrent, asynchronous, distributed, parallel, and/or nondeterministic. It is also a powerful formal method for the analysis of concurrent, embedded, and distributed finite state systems (K. Varpaaniemi, Series A: Research Reports, No. 26, Helsinki University of Technology, Digital Systems Laboratory, Oct. 1993). The reachability analysis of PNs is strategically significant as it captures the dynamic behavior of the system as well as providing efficient verification of the correctness of the model. Few linear programming (LP)-based methods can be found that address the reachability problem, and some of these are suitable for optimal control problems. However, due to an inherent state explosion they are difficult to implement; other methods run easily into deadlock as they lack appropriate mechanisms to avoid the firing of critical transitions (T. Matsumoto and A. Tarek, in Proceedings of the 35th IEEE Conference on Decision and Control, Kobe, Japan, 1996-12, pp. 4459–4468). In this paper an improved and easy to implement method is proposed that combines the Optimality Principle and Linear Programming (OP + LP) techniques to find an Optimal Legal Firing Sequence (OLFS) in PNs. This method can be applied to ordinary PNs with self-loops, avoids deadlocks, and can also be used for general PNs having cycles.

Self-modifiable color petri nets for modeling user manipulation and network event handling

A self-modifiable color Petri net (SMCPN) which has multimedia synchronization capability and the ability to model user manipulation and network event (i.e., network congestion, etc.) handling is proposed in this paper. In SMCPN, there are two types of tokens: resource tokens representing resources to be presented and color tokens with two subtypes: one associated with some commands to modify the net mechanism in operation, another associated with a number to decide iteration times. Also introduced is a new type of resource token, named reverse token, that moves in the opposite direction of arcs. When user manipulation/network event occurs, color tokens associated with the corresponding interrupt handling commands will be injected into places that contain resource tokens. These commands are then executed to handle the user manipulation/network event. SMCPN has the desired general programmability in the following sense: 1) it allows handling of user manipulations or prespecified events at any time while keeping the Petri net design simple and easy. 2) It allows the user to customize event handling beforehand. This means the system being modeled can handle not only commonly seen user interrupts (e.g., skip, reverse, freeze), the user is free to define new operations, including network event handling. 3) It has the power to simulate self-modifying protocols. A simulator has been built to demonstrate the feasibility of SMCPN.

Design and Analysis of Internet-Based Tele-Coordinated Multi-Robot Systems

The coordination of multi-robots is required in many scenarios for efficiency and task completion. Combined with teleoperation capabilities, coordinating robots provide a powerful tool. Add to this the Internet and now it is possible for multi-experts at multi-remote sites to control multi-robots in a coordinated fashion. For this to be feasible there are several hurdles to be crossed including Internet type delays, uncertainties in the environment and uncertainties in the object manipulated. In addition, there is a need to measure and control the quality of tele-coordination. To this end, the measure of force sensed by each robot is suggested and justified as a coordination index. It was proven that if n robots are event-transparent and event-synchronous then they can be teleoperated under random delay conditions to coordinate to any index value, which is feasible under no delay conditions. The design procedure that ensures a system can satisfy a small coordination index was presented and analyzed. In addition, the design and analysis of event-synchronous systems using Petri Nets is detailed. The Petri Net design methodology is presented for both event-synchronous single operator single robot teleoperation systems and event-synchronous multi-operator multi-robot teleoperation systems. The theory developed was tested by bilaterally tele-coordinating two mobile manipulators via the Internet. The experimental results confirmed the theoretical results presented.

Petri net modelling and design of task oriented messaging system for robot control

Manufacturing Message Specification (MMS) is an international standard for shop floor machine control. It defines a set of conceptual schema and an interactive software object known as Virtual Manufacturing Device (VMD). Many systems have been established using this protocol but very few formal methods have been used to build such systems. This paper addresses the problems of the design and analysis of a network-based task oriented messaging system for flexible robot task control using a Petri net. The information and message transfer processes of the MMS systems were analysed. The modelling methodology allows a top down approach by which the net model is decomposed into fine details with clear identification of components which can be realised directly from the model. This approach is illustrated in this paper by a Windows-based robot control prototype system implemented from the Petri net model. The prototype was built using Object Windows Library and the NetBIOS session layer protocol on a PC network.