Colored Petri Net Model Research Articles

Modeling Timestamp Ordering Method Using Colored Petri Net

Concurrency control methods are designed for preserving consistency of database systems when several concurrent transactions are running. Various concurrency control methods were developed that each one is appropriate for special applications and cases. One of the most common methods that guarantee serializability is timestamp ordering method (TO). This method is one of the timestamp-based methods. Conflicting read and write operations are executed such that scheduling of transactions be equivalent with serial schedule that transactions with lower time stamp precedes transactions with higher time stamp. TO is one of the widely used concurrency control mechanisms. This paper presents a hierarchical colored Petri net model of TO that can be used for formal verification of this algorithm. This model can be used as an important component in modeling and verification of database systems.

An optimization model to fit airspace demand considering a spatio-temporal analysis of airspace capacity

The European and U.S. airspace systems are highly congested at certain peak time intervals. Controllers’ workloads have reached generally accepted limits; therefore, many highly demanded sectors are subject to traffic regulations and restrictions during many hours of each day. A lack of a spatio-temporal analysis of the airside capacity management tools generates airside delays at the destination airport in the form of holding or path-stretching in terminal manoeuvring areas, or even during the cruise by re-routing. These emergent dynamics are demonstrated every day by the urgent need for new and better tools for analyzing and making strategic and tactical decisions that neither induce delays nor negatively impact daily operations. This paper presents an optimization model for airspace capacity–demand management that performs an efficient departure time bounded adjustment configuration for trajectory based operations. This optimization model is supported by the 4D trajectories paradigm, in which a discrete event model has been developed to formalize the trajectories’ spatio-temporal interdependencies. Based on the elements and parameters declared on the validated coloured Petri net model, a set of constraints is obtained. By means of constraint programming, feasible solutions for demand–capacity imbalances are proposed for a case study scenario, while the original departure slots are preserved in addition to the airspace users’ preferences. The results obtained show the advantages in terms of capacity and robustness that can be achieved by applying an efficient departure time bounded adjustment configuration.

Holonic coordination obtained by joining the contract net protocol with constraint satisfaction

Present manufacturing systems are facing significant challenges concerning their adaptability. Holonic manufacturing systems are among the technologies that can provide solutions to such requests, if certain conditions are met. As being included in the class of semi-heterarchical control architectures, holonic systems need appropriate coordination and planning schemes, together with validation tools to increase the beneficiaries’ trust. This paper proposes a coordination scheme for holonic systems, based on a mix between contract net protocol and distributed constraint satisfaction problems. The distinct phases of this method are explained, with details referring to the adaptation of contract net protocol. About the constraint satisfaction mechanism, a guide is provided on how a manufacturing problem can be expressed according to this formalism. To validate the introduced coordination scheme, a coloured Petri net model was developed. This allowed several simulation experiments for scenarios regarding a manufacturing system with four robots to be carried out. The obtained solutions showed that the proposed method can determine both the right holarchy related to the manufacturing goal, and optimal plans for robots. Moreover, as proven by the reachability graphs obtained for different goals, the proposed method reached correct results for all goals and diverse constraints, and it determined all possible solutions. An advantage is about how knowledge possessed by different types of holons is efficiently used, without producing an increased communication load. In conclusion, our method can ensure the right trade-off between complexity and optimality, and the attached model can constitute the required link between design and implementation, thus contributing to an easier deployment of holonic systems.

Server consolidation for heterogeneous computer clusters using Colored Petri Nets and CPN Tools

In this paper, we present a new approach to server consolidation in heterogeneous computer clusters using Colored Petri Nets (CPNs). Server consolidation aims to reduce energy costs and improve resource utilization by reducing the number of servers necessary to run the existing virtual machines in the cluster. It exploits the emerging technology of live migration which allows migrating virtual machines between servers without stopping their provided services. Server consolidation approaches attempt to find migration plans that aim to minimize the necessary size of the cluster. Our approach finds plans which not only minimize the overall number of used servers, but also minimize the total data migration overhead. The latter objective is not taken into consideration by other approaches and heuristics. We explore the use of CPN Tools in analyzing the state spaces of the CPNs. Since the state space of the CPN model can grow exponentially with the size of the cluster, we examine different techniques to generate and analyze the state space in order to find good plans to server consolidation within acceptable time and computing power.

Representing network reconstruction solutions with colored Petri nets

The reconstruction of biological networks from experimental time series data is one of the challenges in systems biology. Currently, most network reconstruction approaches usually yield one solution. In contrast, the (automatic) network reconstruction method proposed by Marwan et al. generates all possible minimal solutions fitting the given set of data, and thus reveals all alternative mechanisms to explain the biological phenomena under study. Although this is interesting and helpful, the generated solutions are usually too many and thus difficult to manage. In this paper, we propose the use of colored Petri nets to represent all possible solutions for a network reconstruction problem by encoding each solution as a color. Specifically, we present two folding (coloring) approaches for generating colored Petri net models for a given set of Petri net networks (solutions). To do this, we not only offer a compact representation of all solutions in one colored model for a given network reconstruction problem, but also facilitate the analysis of each solution by choosing its corresponding color. We also give an application of our coloring approaches by taking the phosphate regulatory network in enteric bacteria as example.

Design of a Time Colored Petri Net Model of the Cloud-Based Mobile TV System

Testing requirements in the earlier stages of system design is a necessary step in system development. Mobile TV system has been in the spotlight due to widespread use of smart devices. Nowadays, most people in public transportation watch TV programs on their smartphones. However, this activity consumes a lot of smartphone battery power. The solution to this problem can be a cloud-based mobile TV system, which transfers the energy consuming processes to cloud and enables a prolonged, quality user experience enriched by social interaction. CPN tools provide an environment in which we can efficiently edit and simulate time colored Petri nets. This paper builds a Petri net model with CPN tools in order to evaluate the efficiency of the cloud-based mobile TV system. Since Petri net can become too big to handle when dealing with a complex system, we built a hierarchical colored Petri net. Furthermore, to investigate the response time of the system we built a timed Petri net. The introduced Petri net will help software developers to test the requirements of their cloud-based mobile TV systems.

Automated Test Sequence Optimization Based on the Maze Algorithm and Ant Colony Algorithm

<span>With the rapid development of China train operation and control system, validity and safety of behavioral functions of the system have attracted much attention in the railway domain. In this paper, an automated test sequence optimization method was presented from the system functional requirement specification of the high-speed railway. To overcome the local optimum of traditional ant colony algorithm, the maze algorithm is integrated with the ant colony algorithm to achieve the dynamical learning capacity and improve the adaptation capacity to the complex and changeable environment, and therefore, this algorithm can produce the optimal searching results. Several key railway operation scenarios are selected as the representative functional scenarios and Colored Petri Nets (CPN) is used to model the scenarios. After the CPN model is transformed into the extensible markup language (XML) model, the improved ant colony algorithm is employed to generate the optimal sequences. The shortest searching paths are found and the redundant test sequences are reduced based on the natural law of ants foraging. Finally, the Radio Blocking Center (RBC) test platform is designed and used to validate the optimal sequence. Testing results show that the proposed method is able to optimize the test sequences and improve the test efficiency successfully.</span>

Formal modelling and analysis of DNP3 secure authentication

Supervisory Control and Data Acquisition (SCADA) systems are one of the key foundations of smart grids. The Distributed Network Protocol version 3 (DNP3) is a standard SCADA protocol designed to facilitate communications in substations and smart grid nodes. The protocol is embedded with a security mechanism called Secure Authentication (DNP3-SA). This mechanism ensures that end-to-end communication security is provided in substations. This paper presents a formal model for the behavioural analysis of DNP3-SA using Coloured Petri Nets (CPN). Our DNP3-SA CPN model is capable of testing and verifying various attack scenarios: modification, replay and spoofing, combined complex attack and mitigation strategies. Using the model has revealed a previously unidentified flaw in the DNP3-SA protocol that can be exploited by an attacker that has access to the network interconnecting DNP3 devices. An attacker can launch a successful attack on an outstation without possessing the pre-shared keys by replaying a previously authenticated command with arbitrary parameters. We propose an update to the DNP3-SA protocol that removes the flaw and prevents such attacks. The update is validated and verified using our CPN model proving the effectiveness of the model and importance of the formal protocol analysis.

Deadlock-Free Scheduling Method for Flexible Manufacturing Systems Based on Timed Colored Petri Nets and Anytime Heuristic Search

This paper addresses the deadlock (DL)-free scheduling problem of flexible manufacturing systems (FMS) characterized by resource sharing, limited buffer capacity, routing flexibility, and the availability of material handling systems. The FMS scheduling problem is formulated using timed colored Petri net (TCPN) modeling where each operation has a certain number of preconditions, an estimated duration, and a set of postconditions. Based on the reachability analysis of TCPN modeling, we propose a new anytime heuristic search algorithm which finds optimal or near-optimal DL-free schedules with respect to makespan as the performance criterion. The methodology tackles the time-constrained problem of very demanding systems (high diversity production and make-to-order) in which computational time is a critical factor to produce optimal schedules that are DL-free. In such a rapidly changing environment and under tight customer due-dates, producing optimal schedules becomes intractable given the time limitations and the NP-hard nature of scheduling problems. The proposed anytime search algorithm combines breadth-first iterative deepening A* with suboptimal breadth-first heuristic search and backtracking. It guarantees that the search produces the best solution obtained so far within the allotted computation time and provides better solutions when given more time. The effectiveness of the approach is evaluated on a comprehensive benchmark set of DL-prone FMS examples and the computational results show the superiority of the proposed approach over the previous works.

CacheSIM: A Web Cache Simulator Tool Based on Coloured Petri Nets and Java Programming

Efficient policies should be applied in order to decrease the document retrieval time on distributed systems, the network traffic, admission and content replacement for cache systems. Usually, proposed simulators that aim to select better policies have limitation. As an example, it's difficult to create scenarios with multiple cache systems. Besides, frequently those simulators present a lack of extensibility resources for both custom policies as to include new mechanisms for measuring performance. To address these issues, we developed CacheSIM. It is an extensible platform for simulating distributed cache systems. Using CacheSIM, we can conceive different scenarios based on a hierarchical Coloured Petri Net (CPN) model. We are able to define one replacement policy of fifteen available and one admission policy of two possible ones. Moreover, we can program custom policies and choose them. This paper presents the architecture and native resources of CacheSIM. We have evaluated its extensibility by including two replacement policies based on semantics found in works of the state of the art. We reproduced scenarios and results of those works, as well as we compared to those obtained using native policies. Thus, we can demonstrate the potential of CacheSIM as a simulation tool.

Testing communication tasks in distributed control systems with SysML and Timed Colored Petri Nets model

Nowadays, Distributed Control Systems (DCSs) are commonly used and supersede stand-alone controllers in many industrial applications. Efficient communication is crucial for their proper operation. Unfortunately, there is a lack of appropriate methodologies and tools applicable to small- and medium-sized DCSs, especially for analysis and testing of communication tasks during early development stages. The paper proposes a flexible and efficient approach that fills this gap. It consists of the following steps. At the beginning, communication tasks and their parameters are specified using graphical diagrams from Systems Modeling Language (SysML). Then, the diagrams are used to automatically generate a model of communication subsystem in the Timed Colored Petri Nets (TCPNs) formalism. Finally, simulation of the TCPN model allows to estimate performance of a target system implementation and to predict its behavior in various cases. Thus, potential bottlenecks might be identified earlier and easier, as well as eliminated even before creation of a hardware prototype. The proposed approach has been introduced into the Control Program Developer (CPDev) engineering environment, which allows to program industrial controllers. Appropriate software tools, namely the editor for SysML communication model, the TCPN library with simulation engine, and the testing framework have been prepared.

PERFORMANCE MODELING OF INTEROPERABILITY SYSTEM FOR SME'S

Three stages of resource integration can be distinguished in evolution of IT: the stage of creation and implementation of middleware technologies and means (1990-2000), the stage of modeling and creation of enterprise application integration solutions (1995-2005) and the stage of enterprise service bus (ESB) development and technologies creation (2004-…). ESB concept was born after the need for business integration emerged, especially under the influence of SME’s needs to have sufficient system functionality for affordable price. Problems of creation and performance issues of one of ESB variants – SME application bus infrastructure for interoperability of business subjects are discussed in this paper. Colored Petri Net model for performance evaluation of such infrastructure is presented.

Application of an Improved Colored Petri Net Modeling Method in Certain Missile Training System

In allusion to the need of analyzing complex system, we have proposed a method named multi-grade color Petri net. We for the first time use this new method to analyze a missile training simulator system. This model can accurately reflect the complex environments of the system and avoid the difficulty occurring often in developing accurate mathematics model by using classical research approach.

Conformance Checking and QoS Selection Based on CPN for Web Service Composition

The development of new services by composition of existing ones has gained considerable momentum as a means of integrating heterogeneous applications and realizing business collaborations. More and more Web services with similar function attributes but different QoS are available. The performance of the composed service is determined by the involved Web services. Therefore, QoS properties are crucial for selecting the Web services to take part in the composition, which can identify the best candidate Web services from a set of functionally-equivalent services. Web service composition enables seamless and dynamic integration of business applications on the web. Due to the inherent autonomy and heterogeneity of component Web services, it is difficult to predict the behavior of the overall composite service. Conformance checking identifies failure and conflict of execution of composite Web service that ensures reliable execution. In this paper we use skyline computation to select services for composition efficiently, reducing the number of candidate services to be considered. Then a novel color Petri net model of Web service composition is presented that combines QoS-based optimal service selection and consistence verification. In the model we define aggregation functions, and use a Multiple Attribute Decision Making approach for the utility function to achieve optimal services selection of QoS properties. We also propose a consistence verification approach to identify potential logical inconsistence of the semantic Web service process before the deployment. Proofs are also presented. We evaluate our approach experimentally using both real and synthetically generated datasets.

Analysis of induced Traffic Alert and Collision Avoidance System collisions in unsegregated airspace using a Colored Petri Net model

For rigorously safe aviation, it is of great significance to conduct an analysis of the current and new operations, providing a global perspective of the scenario dynamics and a better understanding of the potential collision occurrence for risk assessment. The objective of this study is to consider a number of the difficulties that are involved when establishing a validation of the Traffic Alert and Collision Avoidance System (TCAS), which constitutes the last resort for reducing the risk of near mid-air collisions between aircraft in a multithread scenario, and to analyze the TCAS logic using a causal model. In this paper, the causal model that is specified in the Colored Petri Net (CPN) formalism is employed as a key approach to analyze quantitatively the state space of a congested traffic scenario in which the events could transform a conflict into a potential collision. It offers a rigorous tool not only for TCAS validation but also for the analysis of a wide range of properties of the TCAS behavior. This CPN model assumes unrestrained initial positions and TCAS II-equipped aircraft; it is demonstrated to be extremely effective for generating all possible future TCAS failure end-states from the current locations, and the Interactive Collision Avoidance Simulator EuroControl simulator is used to illustrate the collision process of a three-aircraft scenario.

Abstract T P206: An Executable Graphical Model for In Silico Prototyping of Processes for Acute Stroke Care

Background: Strong evidence shows neurologic outcomes in acute ischemic stroke (AIS) worsen with delay from symptom onset to thrombolytic therapy. Yet this onset-to-treatment (OTT) time has not decreased in most systems of care over the past decade. Even the in-hospital, “door-to-needle” (DTN) component of this delay is unimproved, notwithstanding exceptions in institutions where innovative quality improvement efforts have borne fruit. Objective: Provide a basis for visualizing, communicating, and simulating stroke care system configuration and performance to facilitate the quality improvement efforts necessary for reducing DTN and OTT times in AIS. Methods: We developed an executable, graphical model of acute stroke care, employing the hierarchical colored Petri net (CPN) formalism. The top level of the hierarchy sets the epidemiologic context, including demographics and background processes like stroke prevention and onset. At deeper levels, we elaborate time-critical processes that contribute to OTT: stroke recognition, EMS activation and transport, and many emergency department (ED) processes. Key ED innovations described in the literature were modeled: EMS prenotification, a direct-to-imaging transport strategy, process parallelism, and telestroke capability. Results: Our CPN model has provided a platform for detailed, realistic prototyping and simulation of acute stroke care processes. The performance characteristics of process configurations with multiple, interacting innovations were evaluated and compared. Conclusions: In silico care process prototyping permits evaluation of proposed innovations in simulated settings. Using an intensively graphical simulation modeling methodology adds value by promoting “visual consensus” regarding care process structure and function, among stakeholders in a quality improvement initiative.

A Unified Authentication Scheme Based on Analytic Mechanism

To resolve security issues and management issues of different Certificate Authorities (CAs), this paper proposed a unified authentication scheme, which will make different Certificate Authorities (CAs) be uniformly authenticated. In addition, it showed the whole structure of the scheme, added an extensional registration number to certificates and designed unified authentication process for the scheme. The unified authentication process was modelled and simulated by Coloured Petri Net (CPN) Tools and verified by analyzing the state space of CPN model. In conclusion, this paper provides a unified authentication service and confirms that the proposed scheme is totally controllable, realizable and feasible. The suggested scheme can enhance the efficiency and security of authentication systems and achieve good results in practical applications.

Delayed Maintenance Model For Deteriorating Track Using Colored Petri Nets

Track maintenance is implemented to maintain track quality to ensure railway safety. Delayed repair is a specific problem in track maintenance due to the long distance travelling or the limitation of the maintenance tool. We want to assess the effects of delayed repairs on maintenance performance and take them into account for track maintenance decision, especially for the condition based maintenance. In this paper, a Coloured Petri Net (CPN) model is proposed to evaluate the delayed maintenance based on track condition for the given repair delays. This model can investigate the effects of the delays and optimize the maintenance decisions. Monte Carlo simulations are performed for different maintenance configurations. The simulation results show that the floor of ratio of repair delay and inspection interval has influence on the maintenance cost. Furthermore, the comparison shows that the condition-based inspection maintenance is better than the periodic inspection maintenance.

Hierarchical Coloured Petrinet Based Healthcare Infrastructure Interdependency Model

Abstract. To ensure a resilient Healthcare Critical Infrastructure, understanding the vulnerabilities and analysing the interdependency on other critical infrastructures is important. To model this critical infrastructure and its dependencies, Hierarchal Coloured petri net modelling approach for simulating the vulnerability of Healthcare Critical infrastructure in a disaster situation is studied.. The model enables to analyse and understand various state changes, which occur when there is a disruption or damage to any of the Critical Infrastructure, and its cascading nature. It also enables to explore optimal paths for evacuation during the disaster. The simulation environment can be used to understand and highlight various vulnerabilities of Healthcare Critical Infrastructure during a flood disaster scenario; minimize consequences; and enable timely, efficient response.

I/O Conformance Test Generation with Colored Petri Nets

This paper explores Input-Output Conformance (IOCO) test generation with Colored Petri Nets (CPN). A test generation oriented CPN model and CPN based IOCO relation is proposed. Feasible test cases are generated by model simulation with the proof of its soundness. The method integrates the merits the IOCO testing theory and the CPN modeling synergistically, and is applied as a nontrivial and competent test case generation approach for practical testing projects. The effectiveness of this test generation approach is demonstrated by a concrete software system. Since the model simulation based test generation process is irrespective with the model size, the effectiveness of the method is enhanced with scalability.